Second (Grader) Impressions of DreamBox

Because I am a tiny bit obsessed, I commandeered my colleague’s computer and 2nd grade daughter, E, and let her play DreamBox for about 45 minutes.

Once again, I am very impressed by the depth and breadth of the activities available. For example, there are quick image activities just like for Pre-K, but instead of five circles, there are multiples of ten beads shown on a 100-bead rekenrek. E wanted to count by fives, but kept running out of time. After a couple of missed questions she switched to a count-by-tens strategy and blew through the lesson. It was really fun to watch a kid come up with a more efficient strategy, simply based on a well-designed activity. 

I had shown my colleague, Meredith, the videos of J, so she asked me to start filming E. I got a fantastic 90 second clip of her next activity.

The goal of this game is to make the same number a different way. In this case you were supposed to use the entire top row and as many additional beads from the bottom row. E has been getting through the lesson pretty easily when this happens:

Ok, so first she shows her awesome strategy for adding 8, which is to add 10 and count back by 2. You can hear her say “two less than 18” before she counts down to 16.

E used this strategy whenever the second addend was 7, 8, or 9. I have no idea what the standards look like for addition strategies, so I don’t know if this is explicitly taught, or something E came up with on her own. Either way, I loved the strategy.

So she uses it correctly on this problem, but when she goes to build her answer, that 17 that she said out loud gets stuck in her head and she builds the wrong answer. At this point, Meredith starts waving at me to stop recording and I swat her hand away because I AM CAPTURING AWESOMENESS. 

DreamBox says “Something is not quite right” but doesn’t specify the exact problem. E has to look back at her work and find her error, which she does. No adult needed to intervene in order for E to catch her error.

Let’s be clear: E knows how to count to 16 and build it in a different way. But she isn’t fluent yet. This is the sort of mistake that happens a lot when a child is becoming fluent with math. And it’s a vital part of the process. Notice how much more quickly she added 8+8 the second time. She is deepening these grooves in her mind as she practices problems that are within her comfort zone but not easy for her.

Then comes the second bit of awesomeness: Open number sentences! She has to represent what she did in an equation. I love this equation because it has a full expression on either side of the equals sign. So already, in second grade, E is learning that the equals sign represents equivalence, not “where the answer goes.” DreamBox even gives her the option of placing 16 in her answer, but she knows by this point in the game that the first number needs to represent the top row and the second number needs to represent the bottom row. Beautiful.

So E does some more activities, like one where she has to add two numbers, except one is expressed as a numeral and the other as a series of dots. Cool stuff.

Then we get to this activity, where I captured yet another AWESOME bit of student thinking.

E has to build her 100-bead rekenrek to match the one in the top left corner. She then has to find the numeral that matches the two-digit number she built.

E starts by counting rows, but she uses her count-by-fives strategy that I saw her use in an earlier activity. Except now she’s counting entire rows by fives. She realizes her mistake partway through and corrects herself, going back to count by tens.

Then she makes that exact same mistake five more times in a row. On every subsequent problem, she counts rows by fives before switching to counting by tens. On the fourth problem, she only catches her mistake when she sees that 25 isn’t available to click. Her mom, Meredith, is losing her mind in the background but doesn’t say anything because she knows that if you want your kid to learn sometimes you just have to shut up and let them make mistakes.

I thought, at the time, that she got the strategy right on the last problem, but watching the video I see that she never fully corrected this mistake. But if I were E’s dad or teacher, I wouldn’t mind one bit.

As I mentioned at the top, E just started using counting-by-tens as a strategy on a previous activity. It’s a new strategy, and one she’s less comfortable with than her count-by-fives strategy. So she’s trying to become fluent with her new idea but her old one keeps getting in the way. She’s regressing a bit in her counting as she tries to upgrade her strategy. Which is exactly what she should be doing. 

Every time I try something new in my classroom, I become a somewhat worse teacher in the short term. When a golfer tries to fix her swing, she gets worse at golf while she acclimates to the new motion. I have no doubt that E will become fluent at counting by tens. But she’s probably going to keep making mistakes for a while. And that’s fine.

I am so glad I caught that moment because it’s a great reminder to me as a teacher that students don’t automatically incorporate new information or correct their own misconceptions. Even if they can catch themselves, they are still prone to error as they build fluency. But as long as I can give them the time and space needed to become fluent. they will be fine.

After this afternoon of watching E play, I am even more convinced than I was last weekend of the value of this program. E is talking the way I want my students to talk and thinking the way I want my students to think. Not only that, after 45 minutes she turned to her mom and said "Can we play this some more when we get home?"

When my trial runs out, I am signing our family up. 

First Impressions of DreamBox

A little while ago, Tracy Zager wrote a fantastic post about the criteria she uses to evaluate math games. Within it, she recommended a program called DreamBox. It looked promising, so I installed it on my school iPad and signed up for a two week trial.

My son J and I just spent an hour playing with the games today, and I am very impressed. This is exactly the sort of math program that I have been waiting for years to see. 

A Ten Frame

A Ten Frame

I am so sick and tired of games that only care about “math facts.” I want a program that deals with math patterns, math representations, and math concepts. DreamBox, at least in the early levels, is full of the sort of math representations that I see in the elementary classrooms I envy. J was working with ten frames and rekenreks, which are fun to play with even digitally. He wanted to play each tutorial twice just because he liked sliding the rekenrek beads back and forth or changing the composition of the ten frame. 

A Rekenrek

A Rekenrek

There are even activities for the youngest learners, those who don’t even have a firm grasp on their numbers from 1-10. There is an early game, “More or Less,” where the game displays two quantities of dots and asks the student either “Which is more?” or “Which is less?” This game was great for J because he didn’t know the word “less.” I said it meant not as many which worked well for him until he got to a 1 vs. 2 problem and said “They’re both less!” I have learned a lot about talking math with my kids from Christopher Danielson, so I was elated to hear him say that. It started a fun little conversation about less and more.

Below, I have put a couple of 2-3 minute recordings of J playing through some other games. I have decided to write-up a detailed commentary of the math that I think is going on in each video. So consider this your chance to jump ship.

Check out DreamBox! I have no connection to this company other than I think they made a cool app. It’s got a free trial for 2 weeks and then costs $13 a month. That’s a pretty steep price. I’m still not sure if I’m going to pay it. We’ll see how the next 12 days go...

A DreamBox screenshot

A DreamBox screenshot

Ok, now down here let’s get reeeeeel mathy. Remember, I am not an expert in this stuff. I am a middle school math teacher, but I have a hobbyist’s enthusiasm for early childhood math. So what I write is not a firm account of what happened in the video. It’s what I think is going on, and what I notice about that. So in the comments, please add your thoughts!

 Video 1

In this game, J has to replicate the top rekenrek using a double rekenrek (these are the abacuses with the red and white beads. I just looked up the name today, so don’t feel bad. I still don’t know how to pronounce it).

The thing is, he must use beads from both the top and bottom rows. I think the purpose of this activity is to get kids to move from a visual understanding of matching towards the idea of equivalence; that is to say, the idea that 2 and 3 are equivalent to 5. So that’s what J is working on.

 

So on the first problem, which I missed, J immediately yelled “2!” when he saw the two red beads. That means J can recognize the quantity 2 without counting the beads. This is known as “subitizing” and it’s a huge early math skill. It depends on the quantity and the arrangement of the objects. Look at the two pictures below. One you can look at and immediately know how many dots there are. The other, you can’t. It’s because the 5 dots are a smaller number and the dots are arranged in a very familiar pattern. The other one you actually have to count because there are more dots and they are scattered across the page.  

J can subitize 1, 2, 3, and sometimes 4. At this point, he hasn’t had to count any of the beads individually so far. So when he sees an amount he doesn’t recognize, he is in uncharted territory and asks me whether he can count. He counts up to 5, moves 4 across, asks me for help which I refuse to give, and then moves the fifth bead across. J then recounts his beads, gets 5, and celebrates by swinging the iPad around. 

Notice that he hasn’t touched the green button yet. The program hasn’t told J that he is right. J already knows for himself that he is right. That is what a conceptual understanding looks like.

Things I did that I hate:

“Now make 3 in a different way” - I did this because I already know (or think) that J can subitize 3, and I wanted him to focus on the mechanics of the game. But I should have said “Now make the next one in a different way.”  Let him do the work. No shortcuts, kid.

“Ooh, this is a hard one, J.” - This is such a tough habit to break. I’ve been a teacher for 6 years, and I’ve been trying to break this habit for 5.9 years. 

It’s so understandable. You want to build up kids’ confidence, so you see a challenging-but-solvable problem and you say “ooh, this one’s hard!” so that once they get it right, they feel smart. But the thing is, how do I know whether this problem is hard? J is going to try the problem in a second anyway. He can decide on his own whether the problem is hard or not. And if you ask him his opinion afterward, he might even tell you why.

But if I start the problem by saying “this one’s hard,” then I’ve already created an artificial sense of difficulty that colors his perception of the problem before he even starts to solve it. This is especially harmful when a child struggles to understand a problem that you’ve called “easy.” Every level of teacher does this, and it always hurts the kids. We start with easy and by middle school we say obvious and in college we say intuitive, but it all means the same thing. Which is “you better get this right pretty quickly or you’re dumb."

It’s better just to let the problem and J decide together whether or not it’s hard.

Things I did that I like:

“I don’t know. Try it.” - This is my standard answer when he asks for confirmation. J is more than 50% confident in his answer, but he’s looking to me to tell him he;s right. I don’t want to do that. I want him to get used to finding possible answers, thinking it through, and testing the ones he feels fairly confident will work. I want him to get comfortable with being uncomfortable.

All the parts where I wasn’t talking - Shut up and get out of the way, Dad. That silence is the sound of someone’s brain growing. Don’t interrupt it.

Video 2

This video was from the next game we played. In this game, you are supposed to make your ten frame match the given frame exactly and then click on the numeral that matches the frame. J is pretty familiar with the numerals from 1-10, but this is one of several games that helps to strengthen that connection. The numbers are laid out in order so you can count up to the appropriate numeral if you don’t recognize it by sight. 

Since we had just been working on equivalence, I think J is just trying to match the quantity. I think he didn’t realize that his ten frame had to look exactly the same as the frame above it. So that’s what I’m explaining to him at the beginning.  

First thing: J can subitize 10 in a ten frame! That is news to me, and very impressive considering he just saw ten frames for the first time today. Unless they’re using them in his pre-school class already, which I doubt, this means he has learned a new idea from DreamBox already. Also, he knows that moving the 10 dots at once is more efficient than moving them 1-by-1.

J decides the next problem, nine, is a tough one without me even saying anything! See, he does have his own internal sense of difficulty. So he counts the nine dots, sings a little adorable Nine Song, and starts to build his nine in a very efficient manner, by starting with the 5-dot piece and then getting the 3-dot piece. Then he concludes he’s done. I try to ask a question without giving away that he’s made a mistake. 

So he counts his frame, gets eight, goes back and counts the original frame, has a little I’m-a-three-year-old moment, and just gets a bit discombobulated. So I ask him to put down the number he thinks it is, and he picks 9. I find this interesting since he didn’t get nine for either of his most recent counts. But the correct answer was still in his brain somewhere. If you go back and look, just after the Nine Song is a moment when his finger hovers over the numerals. I think he was about to pick 9 then, so he made that connection before he even started building the ten frame.

I am in love with this second video. For one thing. I did a much better job of getting out of J’s way and letting him reason through the problem. 

Secondly, I love that J made mistakes in this video. He sees two similar ten frames as being the same, and he doesn’t properly count the original frame on his second attempt. The concept of touching one object per number when counting, which is called one-to-one correspondence, is something that J is decent at but still messes up occasionally. When he gets off track in counting, he starts singing the numbers in sequence but is no longer connecting them to the dots. 

AND THAT IS OKAY. He is a three year old and working on a new skill. I don’t need to stop him and correct him every time I see him make that sort of mistake. The program will catch J’s mistake and over time he will become a more precise counter. I love mistakes. It means that kids are working at the edge of their abilities. And I don’t always correct J, any more than I correct every little grammar mistake he makes. J used “he” and “she” interchangeably for almost a year before he realized that they connoted gender. I never corrected him for months and months. I just used the pronouns correctly in my own speech and figured he’d figure it out when he had a firm grasp of “boys” and “girls” as an underlying concept. And you know what? Almost a year later, he was ready. 

What I care about is that the program found his mistake and asked him to try again. This is one of Tracy’s 3 big criteria for math games, and it’s spot on.

So right after I shut off the video, J picked up a 5-dot piece and then filled in the second row one-by-one until he got to nine. Then he said “It’s easier to do ones” and on the next one, which was a seven, he filled in all seven dots by ones. He shifted to a less efficient strategy that was within his comfort zone. Again, I am fine with this. Over time, he will shift back to using the larger pieces once he finds single-dot pieces too time-consuming to use. I’m not going to force it.

So J, like every other child in the entire world, isn’t a perfectly elegant problem solver yet. But he’s a little bit better than he was at the beginning of the day. Credit where due: DreamBox has put together a very promising app. I am really looking forward to the next 12 days. 

Permit Me to Brag

My Algebra 1 students surprised me. I typically hate grading final exams, but as I was grading my students' exams I noticed something that got me legitimately excited! I was actually, enjoying the process of seeing each new student's work.

Specifically, I wanted to see how they solved problem #16.

When I wrote the question, I had anticipated that students would use a couple of different strategies. What I didn't know was that my 25 students would use a combined seven correct solution strategies to solve this problem.

Here they are, starting with the ones I anticipated.

Eight students started at (7,4) and used the slope to fill out a table or list of points until they reached the point (13,0).

Six students substituted in 13 for x and solved for y.

Four students substituted in 13 for x and 1 for y and got an impossible solution.

Now we get to my favorites:

One student, W, started at (13,1) and worked backwards up to (7,5) to determine that (7,4) was not on the same line.

One student, K, used a coordinate plane from another page to graph the line and then wrote his justification down. He erased the points, but I found them, very faintly, on the next page. 

Clever girl... (Well, he's a boy, but still)

Clever girl... (Well, he's a boy, but still)

One student, E, found the y-intercept of (0, 8 2/3) and then made a table of values from that point until he was satisfied that the line never intersected (13,1).

And my absolute favorite, the most elegant of all the solutions: One student, M, found the slope between (7,4) and (13,1) and saw that it was different from the slope of the line. QED.

Way to go, M!

Way to go, M!

(Side note: Three students got the problem wrong. Two of them substituted the y coordinate in for x, and the last student mixed up her slope and used -3/2 instead of -2/3)

I want to be clear as to why I am so thrilled. It is not because Problem 16 is some deep, challenging math problem. It's pretty straightforward and simply requires an understanding of point-slope form. It's easy to teach kids a procedure to solve it.

But I'm proud because I never explicitly taught a procedure for solving this problem. Instead, I gave a similar problem to my students in class, let them work on it in groups, and shared some of my students' various solution strategies. There was never a moment where I said "Ok, from now on always make sure to substitute this point into this equation to determine whether that point lies on the line described by the equation."

To be honest, I really didn't know at the time whether I was doing the right thing. Sure, everyone got the problem right in class (in groups, with support), but without a single procedure or mnemonic, would they be able to do it again weeks or months later?

The answer, I'm comfortable saying, is yes. My students retained the concept behind the problem. Different students chose strategies that worked best for them. Sure, E did a bunch of extra work when he found the y-intercept and made a table of values. But he used the method that made sense to him. He stopped trying to recall a set of steps and instead said "What can I find out from this information, and how can I use it to solve the problem?" M used the same approach and came up with a strategy that I had never seen until I was grading her exam. Her strategy is so elegant I can't believe I never got the chance to show it off in class!

To be honest, that's why I wrote this post. I want to brag on M. But really, I want to brag on all my students. Other kids came up with cool strategies on other problems. Kids surprised me on a final exam. My students are acting like mathematicians, y'all. They're using their toolkit of math ideas to solve problems flexibly. I couldn't be happier.


 

 

 

 






Ok, if you've followed me down here, you can read this part. I'm still secretly scared that I'm doing it wrong. Every time I get all puffed up and start to crow, a little voice in my head starts talking about how pride comes before the fall. Because after all, E doesn't have an efficient way to solve this problem. For that matter, neither does K. So did I really teach those kids how to solve this type of problem? Duct tape can hold up a light fixture if you use enough, but that doesn't mean it's up to code.

What do you guys think? Should I be proud? How can I keep improving so I reach those students who found creative-but-inelegant solutions? What about the three who missed the question - what do I do about them?

One Week in Mr. Haines's Math Class - Friday

Friday

Warm-up:

I ask students to look at their worksheet from yesterday and pick one acute triangle, one right triangle, and one obtuse triangle. I then call on 3 kids at random to share their side lengths.

Activity:

I've gone through a great deal of discovery work yesterday, so it's time for a little guided instruction. I give a small lecture about the Greeks, who were faced with a similar problem. Except the Greeks noticed something pretty cool that happens when you square the sides...

I square the sides for each triangle and ask students to look for patterns for 2 minutes. In each class, someone noticed that the right triangle's short sides added up to the long side when all sides were squared.

So we use that as a springboard to analyze acute and obtuse triangles. Pretty quickly, we see that acute triangles' short sides add to more than the longest side, whereas obtuse triangles' short sides add to less than the long side. (I keep saying, over and over, "after you square all the sides" like a broken record because I am terrified of students forgetting that step.)

So now we have a hypothesis. How do we test it? Three new triangles! I get three new triangles from my students and try out our hypothesis, which seems to work!

Time for notes in our $1 Textbooks. We write down the Pythagorean Theorem, a diagram with the legs and hypotenuse defined and labeled, and the rule for classifying triangles using only their sides.

Finally, I give students a final triangle worksheet. In this worksheet, they are given the sides but not provided a ruler. They must use this new classification tool to classify the triangles.

If we have time, I've embedded an extension task in this worksheet. In the first problem, we had sides of 6, 8, and 11, which resulted in an obtuse triangle. The second problem, 6, 8, 8, resulted in an acute triangle. What would we need the hypotenuse to be to make a right triangle?

Homework

None

Monday's Goal:

Continue using the Pythagorean Theorem, now finding the missing sides of various triangles.
 

Resources:

Classification Worksheet

One Week in Mr. Haines's Math Class - Thursday

Thursday

Warm-up:

None - we have a lot to do today!

Activity:

I hand out two worksheets - a set of triangles that I have drawn and a worksheet where students will collect their work for the day. I also give out a ruler to each student. The instructions are simple: Using the centimeter side of the ruler, measure all three sides of each triangle. Then classify each triangle by its sides and by its angles.

For the file, check the link above or the Resources section below,

For the file, check the link above or the Resources section below,

I had to hand-draw these triangles using a compass and ruler to ensure that the measurements were precise, but that's fine - I love constructing geometric figures. (In fact, I think kids should spend WAAAAY more time in geometry constructing figures of their own, but that's a side issue.)

This section of the class whips by pretty quickly, and I was able to help out any students who were struggling with using a ruler. They can all use rulers, but only if I really, truly force them.

On the back of their classification worksheet, I list a bunch of triangles by their sides and ask students to classify these triangles by their sides and angles. Pretty quickly, they realize that all the triangles are scalene, but how can you tell whether they are acute, right or obtuse? Mr. Haines? Mr. Haines? Can you come here?

At this point, I am walking from table to table distributing scratch paper and encouraging students to try to draw each triangle. There is a LOT of trial and error as students draw, then redraw, then redraw their 8, 9, 10 triangles or their 2, 8, 9 triangles. I don't worry too much about this. After all, I am giving the students a headache so they appreciate the aspirin.

Also, these are some really clever students I'm teaching! In two of my three classes, I had a student come up with the following strategy, which I will paraphrase:

"I pretend the triangle is a right triangle. So I draw the short side and the medium side with a right angle, and I try to connect them with the third side. If the third side reaches perfectly, it's a right triangle. If it's too short, the triangle is acute because the short side has to bend down to reach it. If the long side is too long, the triangle is obtuse."

Pretty cool, right?

Pretty cool, right?

By this point, we are edging right up against the bell, so I bring the students together, run through a quick check of their classifications, and then ask them why it took them so long. Lots of grumbling about erasing and redrawing. I mimic every announcer from every infomercial eve: "There's got to be a better way!"

The bell rings. Tomorrow, we meet Pythagoras.

Homework

None

Tomorrow's Goal:

Introduce the Pythagorean Theorem and use it to classify triangles.

Resources:

Triangle Worksheet (I tried very hard to get the scale of the triangles to remain after scanning and converting to a PDF. Hopefully this works for you, but it may depend on your printer. Or you could construct your own set of triangles!) 

Classification Worksheet 

One Week in Mr. Haines's Math Class - Wednesday

Before we get into today's lesson, which was my favorite lesson all week, can I rant about something for a minute?

Why in the world would someone try to teach about square roots without talking about squares? I'm not referring to "squares" as in raising a number to the second power. I'm talking about "squares" as in those pointy shapes with all the sides that match each other.

You will notice that I didn't even introduce the notation or the term "square root" until my lesson on Tuesday. This was intentional. I don't want my students to get hung up on this new vocab term or this symbol that kind of looks like a long division sign. No, I just want them thinking about how to find the length of one side of a square that has an area of 73.

So already, on day 1 of this unit, I have students who are accurately estimating square roots. They just don't know that they're doing it yet. They think they're finding the missing side of a square. Once they know that concept and build a strategy to solve that sort of problem, it's not a major shift to tell students "Ok, that thing you've been doing, where you un-square a number? That's called a square root. And it looks like this check-mark-with-a-bar-next-to-it symbol you've noticed on your calculator."

Conversely, if you start this unit by projecting a slide entitled "Square Roots" and introduce all the formal vocab and symbols from the start, then students don't have anything to ground their understanding of the operation. You are asking students to use a new symbol to enact a new operation that they've never tried before. And forget about asking them to find the missing side of a square - that would be a seemingly-impossible task to those students.

Introduce the challenge first. Once students understand the challenge, then provide the notation and the vocabulary. Don't dump them both into students' laps at the same time.

Ok, rant over.

Warm-Up:

None. We are diving into the main part of the lesson, something I have been dying to try since I saw Andrew Stadel post about it back in August.

Activity: Movable Number Line

My number line is huuuuge. Great for class, hard to capture in a picture.

My number line is huuuuge. Great for class, hard to capture in a picture.

Ok, so this might have been the most awesome thing I've done all year. I made a loooooong number line out of a string that stretches almost all the way from my window to my door. I put the numbers 0 and 10 on either side of the number line.

I told kids that I would be showing the whole class a number and then calling on one person to place that number on the number line. Nobody else could talk, but we would take a poll after the student sat down:

  • Thumbs Up: Perfect!
  • Thumbs Sideways: Your answer is in the correct order but needs to slide either right or left
  • Thumbs Down: Your answer is out of order

Then I held up the number 4. I chose 4 on purpose because it's incredibly familiar to students and yet a bit tricky to place. It's closer to 0 than to 10, but how much closer? Not to mention, with such a long number line, it's going to be hard to get the placement exactly right. I was expecting a lot of "Thumbs Sideways" on this first number, and I wasn't disappointed.

By the way, I use popsicle sticks with names, often called equity sticks, to choose my participants in class for this activity. I know that some teachers feel that equity sticks cause students anxiety, but I think they are worth it for this sort of activity. First of all, they strongly improve engagement. Everyone knows that they could be called up to place the next number, so they are paying attention to each number I present. Secondly, this activity does not have a clear right-or-wrong answer. In fact, I usually end up polling the class and sliding each answer ever-so-slightly in one direction or the other. Since every answer gets improved or amended, the pressure to be exactly right is lowered. Everyone is just making their best guess.

But back to the game. The first student has just placed the number 4, and we have to decide - is it perfect, or should it slide right or left? In my first class I had a student place 4 verrry close to 0. This is a great opportunity to ask students to critique the reasoning of others in a respectful way. I had lots of great comments from students, such as "If 4 was that close to 0, you wouldn't have room for 1, 2, and 3, and you'd have way too much room for the numbers bigger than 4." As the lesson went on, the justifications became more precise.

My next choice, root(49), I chose because 7 is exactly halfway between 4 and 10, and I want to see fi my students will pick up on that.

My third choice, root(20), is where the real fun starts. Now students have to use yesterday's skill of estimating square roots without any benchmarks. Where should root(20) go? Where is 5 on this number line? Where is 6? These are all questions that my students are silently asking themselves as I hold up the card with root(20) on it. At least, it sure seems that way. My students are rapt. They can't wait to find out if their popsicle stick will get pulled.

From here, my sequence was 6, root(93), root(40), root 4, root(14), root(-4). I'm sure I could have sequenced them better, but I'm not sure how. How would you sequence this activity? Let me know in the comments.

Are these placed appropriately? If you could slide one card, which one would you slide, and where?

Are these placed appropriately? If you could slide one card, which one would you slide, and where?

Are these placed appropriately? If you could slide one card, which one would you slide, and where?

Anyway, I like this lesson for a few reasons:

  • Student engagement was through the roof. I felt like everyone was with me in a way that almost never happens. Kids were having fun! I even had a group of students ask me in study hall the next day if they could play "the number line game" again
     
  • Because the number line is huge, almost nobody placed their card in exactly the right spot on the first try. We always had to shift someone's card a little to the right or the left. Conversely, almost nobody put their card in the wrong order. So all the students were participating in an activity where nobody got an answer totally wrong, but nobody got an answer totally right. The pressure that students feel when coming to the front of the class was lessened in this case. Sometimes, students had a legitimate difference of opinion and we had to agree to disagree since this activity has an inherent amount of imprecision. But that's great! I'd rather my students be disagreeing and debating as long as they back up their ideas with some evidence
     
  • By placing radicals on a number line, students are beginning to interact with radicals as objects that have a specific value. It's not just a problem to be solved. Root(14) is a number that is somewhere between 3 and 4. That approach to radicals will be useful in Algebra 1.
     
  • I threw root(-4) in as a challenge because I thought it would spark a great debate. I also wanted to add a little bit of new information into the day's material. Yes, it's a trick question. Maybe it will feel more memorable to students because they spent 3 minutes arguing over the location of root(-4) before I admitted that there is no place for this answer on the number line. At least, not this number line.

This took about 30 minutes, which sounds crazy, but it was my first time trying a number line, and we had great discussions between every number.

Here’s a good extension. Start with numbers other than 0 and 10. Here I’ve started with 2 and 8. Where would you place root(36)? Root(90)? Root(3)?

Here’s a good extension. Start with numbers other than 0 and 10. Here I’ve started with 2 and 8. Where would you place root(36)? Root(90)? Root(3)?

Once we had placed all the numbers on the number line, I pulled more popsicle sticks and got students to sort the numbers on the number line into the categories "Rational" and "Irrational." This is my attempt to cement the idea of irrational numbers within our existing activity. Kids could sort the numbers perfectly, but I still don't know if they truly understand what irrational numbers are, and how they actually differ from rational numbers. Something to think about before next year.

Lastly, I got students to create a foldable for their $1 Textbooks to help them classify triangles by their sides and angles. This is vocab that they should know, but it's going to be vital for tomorrow's activity, so it's worth the time investment to make a good foldable.

Note to self: draw triangles in the foldable so kids don't draw their own "obtuse" triangles that are clearly acute.

Homework

IXL Activity on estimating square roots. I am lagging in my implementation of lagging homework. I'll get better at this.

Tomorrow's Goal

Classify triangles by their sides and angles, maybe even discover the Pythagorean Theorem?

One Week in Mr. Haines's Math Class - Tuesday

Tuesday

Warm-up:

I give my students a worksheet with three problem types:

  • Find the area of a square
  • Find the side length of a square whose area is a perfect square such as 25, 36, 49, etc,
  • Estimate the side length of a square whose area is given but not a perfect square.

I like recapping every problem type from yesterday since it reminds students of our progression on Monday. It also provides an easier on-ramp for students who were absent on Monday.

The only difference today is that students are no longer allowed to use calculators. I want them developing their own strategies to estimate square roots.

Activity:

Once we've reviewed the questions from the warm-up, I ask students to get out their $1 Textbooks. This is my name for my class's interactive notebooks. I was skeptical of the time commitment required to do interactive notebooks well, but this year I buckled down and got it started. I realized that I don't use a textbook in my class, so it's my responsibility as a teacher to provide a resource to students so they can review the vocabulary and concepts that they are responsible for in my class. We write in our $1 Textbooks about 2-3 days a week, and rarely more than a single slide or two of notes. But at the end of the semester, my students have a marvelous study guide for their final exam.

We write down some review material about squaring numbers, and then I give a short speech about square roots and what that term means to me. I say that trees come in all shapes and sizes, but the thing that fundamentally determines their size is their roots. Similarly, squares come in all sizes, but their size is determined by their "roots," which is the size of the base. If you want to draw a square with an area of 25 square inches, you need a square with a root of 5 inches. This is a bit of a silly analogy, but it provides some hook for this new vocab.

Once we write down our notes on squares and roots, I ask students to turn to the back of their warm-up sheet. Along the top you'll see that I ask students to calculate the squares of the numbers from 1-10 and then find or estimate a bunch of square roots. I provide the top line because I know that some students will not immediately come up with their own strategy for estimating square roots.

Almost every student can find the square roots of perfect squares because the first row of the worksheet acts as an answer key. So if a student is having trouble with estimating roots, I ask them how to find the square root of 81. Then I ask why they are having trouble with the square root of, for example, 38. When they say something like "38 isn't in this list of numbers," I ask them to find the square number that is closest to 38 but a bit smaller. Then we find the closest square number that is close to 38 but a bit too big. We use those numbers to make our estimate, which should be between 6 and 7.

Once most students have completed the worksheet, we check the work as a class. I typically project my own worksheet using a document camera. I don't love that I have to sit in the back of the room, as I can't read my students' facial expressions. But I like being able to manipulate the worksheet itself. That way my students can easily scan my sheet and their own to check their answers. Also, while I am writing estimates on the worksheet, I can find the square root using my calculator and show that on the document camera as well.

By this point, most students have noticed that all these square roots of numbers like 47 and 6 keep going to the end of the calculator. So I go into a quick math lesson about rational numbers, and how ancient Greeks thought that they were the only type of number that existed until they tried to find the area of a circle. I know this history lesson is rough (and not exactly accurate), but it taps into my students' prior knowledge of pi and helps them to believe that the square roots of certain numbers are  also irrational.

Then it's time to write down some notes about rational and irrational numbers in our $1 Textbooks before the bell! Not the best time to introduce new vocab, I know. I'll have to remedy that tomorrow.

Homework

IXL work on finding the square roots of perfect squares. My goal is for everyone to say "Mr. Haines, I finished the homework in like 2 minutes!"

Tomorrow's Goal:

Build fluency with estimates of square roots.

Resources:

Squares and Roots Worksheet



One Week In Mr. Haines's Math Class - Monday

Sometimes I read about a great lesson or idea, but I am not sure how the teacher strings all these ideas together. So I’m going to blog about an entire week of teaching and explain how I tried to meld together several different types of lessons.

Weekly Goals:

My goals are for students to meet the Common Core standards shown below: 

CCSS.MATH.CONTENT.8.NS.A.2

Use rational approximations of irrational numbers to compare the size of irrational numbers, locate them approximately on a number line diagram, and estimate the value of expressions (e.g., π2). For example, by truncating the decimal expansion of √2, show that √2 is between 1 and 2, then between 1.4 and 1.5, and explain how to continue on to get better approximations.

CCSS.MATH.CONTENT.8.NS.A.1

Know that numbers that are not rational are called irrational. Understand informally that every number has a decimal expansion; for rational numbers show that the decimal expansion repeats eventually, and convert a decimal expansion which repeats eventually into a rational number. 

CCSS.MATH.CONTENT.8.G.B.6

Explain a proof of the Pythagorean Theorem and its converse.

CCSS.MATH.CONTENT.8.G.B.7

Apply the Pythagorean Theorem to determine unknown side lengths in right triangles in real-world and mathematical problems in two and three dimensions.

That’s a whole lot for one week! To be fair, there is a lot in these standards that I won’t be getting to. Here are my more specific learning goals:

  • Find the square root of perfect squares
  • Estimate the square root of other numbers
  • Understand the difference b/t rational and irrational numbers, and know that many square roots of whole numbers are irrational
  • Classify triangles as acute, right, or obtuse based solely on side lengths using the Pythagorean Theorem
  • Find the missing side of a right triangle using the Pythagorean Theorem

Still, it’s ambitious. And to be honest, I wasn’t sure on Monday if I would even get to the missing side of a triangle. Fortunately, I have 3 days next week to use and apply the Pythagorean theorem before exam prep starts. So if I only get through classifying triangles, I’m happy.

Monday

Warm-up: Number talk about the problem 14*8.

This is the only day this week that I did a warm-up that was not connected to the material. I wish I had done more warm-ups, but unfortunately as the semester exam approaches I get nervous about running out of time. My favorite method a student used was to multiply 7*8 to get 56 twice, then add 56+56=112. 

Activity:

I handed out this worksheet. The front asks students to find the area of squares. I know that geometry is my students’ weakest topic in our standards, so I try to start at the very beginning. Some students didn’t know or remember how to find the area of a square. Is this shocking to me as an 8th grade teacher? Definitely. But I just walked around the room with blank graph paper. If a student couldn’t find the area of the first few squares, I asked the students to draw each square on graph paper and count the number of boxes inside each one. Every student pretty quickly realized that they could multiply the base of the square by its height.

The bottom half of the worksheet I included non-integer side lengths to prime the students for the possibility that squares can have side lengths other than whole numbers. This will come in handy on the back of the worksheet when they have to estimate square roots. In my A period class, I didn’t allow calculators, but so many students were having trouble multiplying with decimals that I let them use their calculators. After all, fluency with the multiplication algorithm isn’t the point of this lesson. Noticing patterns in square numbers is the point of the lesson.

(My favorite part of this activity was the student who got 36 instead of 1/4 as his answer to problem 6, which had a side length of 1/2 ft. I asked him how he got 36 and he said “Well, I know that half of a foot is 6 inches, so I changed the measurement to inches and got 36 square inches. Am I allowed to do that?” High fives all around.)

Then we moved to the back of the worksheet. On the back, I provide the area of each square and  students have to find the side length. I was prepared to walk around with graph paper again so students could try to draw a square with 36 boxes in it, but nobody seemed to need it. Kids blew through the first four problems.

The bottom half of the worksheet was harder. I had kids saying “I can’t find any number that multiplies to 19,” to which I replied “What’s a side length that’s just a little too short?” Kids would usually say that 4 was too short since it gets an area of 16. Then I said “What’s a side length that’s just a bit too long?” and kids would usually answer 5.

So I would say “Hmm. 4 is too short, but 5 is too long. Weird.” and walk away. By this point in the year, the kids are used to me doing stuff like this.

(Note: Initially I used A=20 instead of 19, but I had two students who thought the best estimate was 4.5 because 4*5 =20. Then they put down a side length of 6.7 for A=42 since 6*7=42. These are both decent estimates, but for the wrong reasons. I changed problem 5 to A=19 to avoid this misconception in the future.)

Some kids came up with decent estimates for all four problems on the bottom half, while others got stuck on problem 5. Kids would show me their answers and I would ask them if they got exactly 19. Invariably they would be reeeeally close but not quite. With about ten minutes left in class I said “Competition time. The table who gets the closest answer to problem 5 wins a jolly rancher.” With this added incentive kids were furiously plugging numbers into their calculators and refining their estimates.

I would always get one or two kids in each class who knew how to use the square root button, but they only shared their solution with their table since they didn’t want to jeopardize their chance of getting a Jolly Rancher. 8th graders are teenagers, but they are still kids.

With 5 minutes to go, I collected all their estimates on the board and we tried them out as a class. Usually one table had the “right” answer of 4.358898944, which gets exactly 19 on the calculator. But I told the kids that they were ever so slightly incorrect. In fact, if they had a more precise calculator, they would see that their answer was only correct when rounded. We finished the class talking about the fact that the answer seems to keep going and going into the decimals without stopping...

Homework

Students did IXL homework on exponents, reviewing a concept from last year. I am trying to do lagging homework or “refresh” homework when I can, but I am still not good at it.

Tomorrow's Goal:

Introduce square root notation, work on estimating square roots.

Resources:

Squares and Roots Introductory Worksheet

 

Open Equations - Getting Students To Solve Equations Creatively

I ended my last blog post wishing that my students had the chance to solve equations creatively. I think I have found a structure (heavily influenced by Chapter 5 of the book Thinking Mathematically) that will give students this opportunity.

I am going to call these open equations. Here’s how they work:

I project an equation, such as a + 5 = b + 8, on the board.

I ask students to spend a few minutes finding at least three sets of values for a and b that make this equation true.

Then I give the students an additional few minutes to compare their answers and look for any patterns in the responses.

Then I lead a number talk with the whole class as we discuss possible solutions and any patterns that emerge.

I like this format for several reasons:

  • The right side of the equation is an expression instead of a numerical value. This is intentional. I want students to stop thinking of the equals sign as the place where the answer goes and start thinking of it as a symbol that connects two equivalent expressions. I want kids to think “Whatever I make a and b, I need to make sure that a + 5 has the same value as b + 8."
  • The fact that this is a two-variable equation gets kids away from finding the answer and towards finding some answers. I think this is an important distinction because it leads kids to look for patterns within their answers, something that students rarely do when solving a problem like 2x + 3 = 15. In this problem, students might think “Wow, it looks like a is always 3 greater than b. Why is that?" 
  • This practice of finding pairs of values that make the solution true will be quite valuable when students begin learning about functions. Graphing a linear function just becomes another way of representing all the possible solutions for an equation. Which is exactly what the graph of a function is!
  • In this format, the way students look at the expressions a + 5 and b + 8 is different than the way that students often look at the expression 2x + 3 in the problem 2x + 3 = 15. In the latter problem, students often view that expression as a series of steps that need to be undone. They go operation hunting in order to solve the equation without considering that 2x + 3 is an object in and of itself. I want kids to think of a + 5 and 2x + 3 as things. That’s how I view them and how I think other fluent algebraic thinkers see them as well. Fluent readers see sentences as things as well as seeing each component of a sentence on its own. Fluent writers know how they can manipulate the components of a sentence and still maintain its original meaning. I want my students to be fluent algebraic thinkers. I want them to see the forest and the trees.

I’ve given one simple equation above, but there are a lot of other examples that I think could help students with any number of math topics.

Are students simplifying their expressions incorrectly? Give them the open equation a - 7 + 10 = b and ask students why b is always 3 greater than a.

Are students having trouble combining like terms? Give them an open equation like a + a + a + a = b + b + b. Students will pretty quickly move from adding to multiplying a by 4 and b by 3. If you want, there is a bonus lesson about proportionality in this equation!

Want to explore the distributive property?  Give students the open equation 2(a + 5) = 2b + 10 and ask them to find three pairs of answers. Why are the values of a and b always the same? Could I rewrite the equation as 2(a + 5) = 2a + 10? Can any students write another open equation where a and b are always equal?

Most importantly, I think that this format becomes more successful the more frequently it is used. I use them as warm-ups and like to think of it as a slow-motion number string, but you could work through several equations in a row if the need arises.

I have many, many more ideas for how open equations can be used as a gateway to solving equations. And I will be writing a lot more about those ideas and fleshing them out online and in my classroom.

But the purpose of open equations is not to get students to be better at solving equations. The purpose of open equations is to get students to understand equations. Once they understand how equations relate two equivalent quantities, then they can build their own strategies to solve problems like 2x + 3 = 15. And when we move from informal to formal strategies, they will have a basis for understanding those formal strategies and why they work.

Let me know what you think!

Stop the Operation-Hunting

I’d like to talk about an incredibly common mistake that students make when simplifying expressions. And I’d like to talk about why I completely empathize with students and see why they must be so flabbergasted when this problem is marked wrong.

First, the mistake.

1.JPG

The amazing thing about this type of mistake is how insistent my students are that they have not made a mistake at all. For the most part, my students feel ill at ease when simplifying expressions, but this problem feels like sturdier ground to them. And yet it is wrong! How can this be?

I think that students’ confusion comes from a very understandable place: order of operations. When most students learn about order of operations, they learn it as a process of operation-hunting. They look for each operation in turn and then grab the number to its left and right in order to evaluate the problem. Normally, it looks something like this:

Why do you multiply 5 and 4? Because those are the numbers connected by the multiplication sign, of course! Ditto for the subtraction and addition signs.

So a couple of days or weeks later, you ask your students to simplify 5x - 7 + 10. They start their operation hunt. First they find the implied multiplication of 5 and x, but since that can’t be simplified, they move on. Then they find the subtraction sign, but since 5x and 7 aren’t like terms, they can’t be subtracted. So all they have left is addition! Grab the number on the left and right and evaluate! Simple as pie.

This is why kids are so baffled when I mark this answer wrong. It feels like a repudiation of their well-earned knowledge about the order of operations. And it is! At least, it’s a partial repudiation. It tells students that they cannot simply hop from operation to operation, excusing one’s dear Aunt Sally until the final answer has been derived. And this tension between order of operations and the fundamental properties of math is hardly addressed.

In the past, I have tried to remediate this issue by drawing boxes around the problem like so:

This doesn’t really make sense to students. First of all, since when can you put a box around part of an expression? The“- 7” doesn’t look like a valid math expression and neither does “+ 10". It's a fundamentally different way of looking at the problem than the way that I've taught them to look at 5*4 - 7 + 10. But they go along with it, I suppose, because I am big and loud and insist that this is the cool new way to think about simplifying expressions. Forget what I said in late August! It’s early September, for God’s sake!

But really, does this make any sense? Would it work with the aforementioned order of operations problem? What would you do if you saw one of your students with this work on their paper?

The curse of operation-hunting is the problem, and it must be stopped. We need students to learn the order of operations, of course, but we need to spend much more time working with kids to figure out when the order of operations can be overruled, and why.

We need kids thinking creatively about simplifying expressions. 

But how in the world do we do that?

This post is the second in a series.

The Two Types of Math Mistakes

I want to talk about the two types of math mistakes I see in my class, and why I get so excited by the first type and so depressed by the second type.

First, the mistakes. 

Problem 1: Big Horn Ranch raises 100 horses on 150 acres of pasture. Jefferson Ranch raises 75 horses on 125 acres of pasture

Problem 2:  x + x + 4 = 22

The first mistake is an error in reasoning. It's incredibly common when students are attempting a new or unfamiliar problem. Students try to apply their previous, incomplete understanding of math to a new situation and find that they don't have the tools or the understanding to get the right answer.

This mistake is exciting because it represents the beginning of a conversation. This student reasoned his way to an answer that satisfied him. All I need to do is create some dissonance within his mental model of the problem in order to get him to re-evaluate the problem. Maybe I give another more extreme set of acres and horses that are also 50 apart, such as 60 acres and 10 horses, and ask if this ranch also has the same amount of acres per horse. What about 51 acres and 1 horse? My next step depends on the student and the setting, but at least it's building on some prior understanding of the scenario.

Mistake #2 is a different animal entirely. This is not a mistake that my student reasoned her way into. This is a mistake made by someone with no understanding of equations who is desperately trying to recall some long-forgotten rule about subtracting x from both sides.

More distressingly, this is clearly a student with a lot of experience solving equations. There is no chance that this student would have tried subtracting x from 18 if she were a true novice at solving equations. And if you asked her to explain why she subtracted x from 18, she would likely have nothing meaningful to explain about preserving equality or finding the value of x. She would probably say something about "getting rid of the extra x's" and look at me terrified that I was going to ask her a follow-up question. Even her final answer of x = 17x shows that she has no consistent understanding of what a variable is and how it can be manipulated in an equation.

The second mistake depresses me because it is a mistake that I helped to create. I have taught this girl how to solve equations for weeks. And she has emerged from that experience with a worse understanding of equations than when she began. If I had given this to her on the first day of school, she probably would have at least tried to guess-and-check her way to an answer. And that would have been so much better! At least that would show that she understands the purpose of the exercise.

But no. Somewhere along the way, I helped to break something inside her head. I pushed her up the ladder of abstraction too quickly, and now she's swinging in the breeze. And fixing that issue becomes a twofold challenge. First she must unlearn before she can even begin to learn.

Almost all the mistakes the students make when solving equations are this second type of mistake. And that's something I'm going to try to change.

This post is the first in a series.

Open Number Sentences: Is this _____ actually useful?

Michael and I can’t stop gushing about the Project Z resources and how they have sharpened our thinking about teaching and learning integers.

One of the most eye-opening pieces of their work is a set of videos of 1st and 2nd graders solving math problems such as ___ + 5 = 3 and 2 - ____ = 6. It’s amazing to listen to little kids talk through the exact same ideas that our 7th and 8th graders struggle to understand.

One amazing moment occurred in the second video on this page.  Violet, a 2nd grader, correctly answered -4 to the problem 2 - ___ = 6. She giggles nervously at her answer, but when the teacher prompts her to explain her reasoning, she (adorably) says:

“Because it always goes the other - a negative number to me, when you’re adding or subtracting it, it goes the other way than it usually goes with a positive number.”

That is basically a summary of big ideas 2 and 3 from my previous post. In fact, her phrasing may even be easier to understand than my own!

But I think a great deal of her success is due to the format of the question. I am going totally off of intuition here, but I don’t think she would have gotten the correct answer as easily if she had been given the problem 2 - (-4) = ____.

When students are given a standard problem such as 2 - (-4) = _____, I think two thoughts run through their heads:

This problem is different than 2 - 4 because one of the numbers is negative

Subtraction makes numbers go down

Except in their heads, I think it sounds a lot more like

This problem is differ-  Subtraction makes numbers go down!!!!!!!!!

There is an enormous imbalance between the new, dissonant math problem and the old, well-worn grooves that addition and subtraction have made in students’ minds. This is why integer addition and subtraction are so much harder to teach than multiplication and division.

With multiplication and division, you are just adding a rule about negativity on top of the existing structure of multiplication and division facts that kids already know. But with addition and subtraction, what is happening in the problem is the precise opposite of what students have seen for years and years. Imagine the nightmare it would be if multiplication and division worked this way as well: Imagine explaining that 10 * (-5) = -2

But with the open number sentences, the problem directly confronts students’ preconceptions about addition and subtraction. Look at a problem like 9 + ____ = 4. This problem insists that addition can make a number smaller. It’s up to the student to figure out which number has that effect.

This creates a subtle but important change in the sequence of teaching integers. Typically in my classroom, I present the following idea:

Adding a negative number makes the answer smaller

But the open number sentence turns this single idea into a two-parter.

Part 1) Sometimes addition makes the answer smaller

Part 2) This happens when you add a negative number

I like the open number sentences such as 9 + ____ = 4 because it drops kids right into the space between Part One and Part Two. They first have to grapple with the idea that addition can make an answer smaller. After all, it’s right there in front of them!

Then they have to decide what sort of number would have that effect. Students as young as Violet with an intuitive understanding of negative meaning “opposite,” so it stands to reason that they would gravitate toward negative numbers as an answer.

This is the part of my post where I want to disclaim again: I am 100% speculating based on my personal experience and intuition about teaching integers. I have no idea if these sorts of problems have a meaningful effect on the way kids think about integers. So I will be seeking out research on this topic. If I don’t find any, I might have to make some of my own...

 

Integer Arithmetic - Contexts Aren't Enough, So Which One Should We Use?

Michael, the Project Z research you found on the ways students view integers has shaken my preconceptions as much as it has shaken yours. They have led me to take a big step back and try to look at this unit more holistically.

As an algebra teacher, I think that integer addition and subtraction boils down to three big, interconnected ideas:

  1. Addition and subtraction are opposite operations, or inverse operations. That means that they have the opposite effect when operating upon two numbers
  2. Positive and negative numbers are opposites, or additive inverses. That means that they have the opposite effect when added to a number
  3. Subtracting a number has the same effect as adding its opposite

Everything in my teaching of integers is aimed at these three big ideas. And this research has really helped me think through the ways that students come to understand these ideas.

In your last post you did yeoman’s work trying to connect each of CGI’s addition and subtraction problem types to word problems involving integers.  The issue, as you discovered, is that not every problem type lends itself to easy interpretation using a real-world context. This is also discussed in one of the Project Z presentations, in which the authors state:

"These problems involve context, and when we set out to think about integers, we looked at contexts. But interestingly, we found that when we gave students contexts, such as owing money or increasing or decreasing elevation, they generally avoided using negative numbers. I can talk about a debt as negative dollars or a loss of yards in football as negative yards, but when was the last time you watched a football game and someone said, “Wow, that guy just gained negative 3 yards?.”

Well, damn. So at best, these contexts can get our students part of the way toward a comprehensive understanding of integers. The rest of the battle, which is a subject for a later post, probably has something to do with number lines and open questions like 5 + ___ = 2.

Still, there is at least some value to finding a context that builds a basic understanding of how negative and positive numbers interrelate. And I think I have found one. Or at least, I have found a context that seems very promising.

But first, a game.

You are in a hot air balloon. Sort of. This hot air balloon is different from normal hot air balloons. It is a lawn chair is held in the air by a series of small balloons, each of which can raise your lawn chair by 1 foot. It is also held down by several sandbags, each of which lower the height of the lawn chair by 1 foot.  For the sake of consistency, let’s start the balloon at a starting height that we will call 0, and let’s say that your lawn chair currently has 5 balloons and 5 sandbags attached.

Your opponent also has a lawn chair held up by 5 balloons and held down by 5 sandbags, also starting at a height of 0. Your goal is to raise your lawn chair up to a height of 10 feet above the starting position. To do this, you and your opponent take turns drawing cards. You do what it says on the card and change the height of the lawn chair accordingly. The cards look like this:

But there are also some wild cards that are a bit more complicated:

The first person to raise her lawn chair to 10 feet above starting height wins!

You have a player token and a vertical number line to keep track of your progress. You can use 2-color tokens to represent balloons and sandbags, or any other manipulative you wish.

I have no idea if the mechanics of this game make it fun, or whether ten feet is too easy/too hard to achieve. That part I can tweak later. This game has the main thing I want, which is students grappling with the effect of adding and removing (adding and subtracting) balloons and sandbags (positive and negative numbers). The formal symbols, as always, can wait. I am trying to build a conceptual framework first.  

So after students play this game a time or two, I would give them the following set of questions:

1)  Go through your deck of cards and pick out the three cards you think are most helpful to your chances of winning the game

List those cards below.

Why did you pick these three cards? Explain

2) Now go through your deck of cards and pick out the three cards that are most harmful to your chances of winning the game.

List those cards below.

Why did you pick these three cards? Explain.

3)  Now go through your cards and pick out two cards that had no effect on your lawn chair’s height.

List those cards below.

Why did you pick these two cards? Explain.

N.B. I asked students to list 3 cards in questions 1 and 2 even though there are 4 cards that are the most helpful: Add 4 balloons, Remove 4 sandbags, Add 3 balloons, Remove 3 sandbags. I do this intentionally with the hope that students will get different answers and end up debating whether removing 3 sandbags is “the same” as adding 3 balloons. Again, no formal symbols yet. Just laying groundwork.

The third question gets to the big concept number 2: Positive and negative numbers are additive inverses. I want students to realize that sandbags and balloons cancel each other out.

From here, I have lots of ideas. Here are a few:

  • Play a second version of the game, but every card has two instructions. For example “Add 3 balloons and add 4 sandbags,” or “Add 1 balloon and remove 3 sandbags.” After the game, have students rank the cards from most helpful to least helpful
  • Ask a series of questions such as “Mr. Haines wants to add more sandbags to his lawn chair, but he doesn’t want his lawn chair to go down in height. How can he accomplish this?
  • Ask a series of questions such as “My lawn chair is at a height of 4. I want to get it down to a height of -2. What are some ways I could do that? List as many as possible”

Then, at some point, we transition to problems such as 4 + (-7) = ____ and 5 + ____ = 2. But maybe, just maybe, the students will come to understand those ideas more quickly because of the significant time they spent analyzing balloons and sandbags. How, you say? I have no idea. I haven’t tried it yet. But I think it’s at least worth investigating.

In order to make this transition, you need a lot more than one day of connection. It’s not as simple as Monday: Sandbags and Tuesday: Negative Numbers. Students need to make their way up and down the ladder of abstraction until they know where the rungs are without looking down. Give students a problem such as “add 3 balloons and 4 sandbags” and ask them how you could represent it with math symbols. Give students a problem like “-2 + 5 = ___ ” and ask them to write a word problem about hot air balloons to match it.

Not everyone is going to reach 100% fluency with this model. As I mentioned above, students can and will avoid negative numbers whenever possible. But this might be a good starting point for a unit on integers.

Or maybe not! But I'll play the role of context optimist for the time being. It's more fun to argue.

Use Red Pen - My First Video

This is the first video I've ever made about teaching. Basically, about a year ago I was complaining at a lunchtime PD session about the 14,563rd time someone has told me to use green pen. I decided that instead of inflicting my rant upon my colleagues again (or god forbid, my wife), I would rant into a lens. And here is the result.

To be clear, this video is as much a reminder to myself as it is advice for anyone else. I struggle to make sure my comments and questions on graded work are worth students' time. I want to help my students with my assessment system, and when I get lazy I look at my red pen and remember to try harder next time.

Teaching Integers - Common Contexts

Howdy folks!

This is the first in a series of posts from myself and Michael Pershan about teaching integer operations. In this series, Michael and I are going to discuss the many contexts and strategies that teachers use to teach integers. We will then try to categorize integer problems into several problem types and analyze how these problem types are explained using these different contexts and strategies. Hopefully along the way we will actually learn how to teach integers, but no promises on that count!

Integers feel like a topic in middle school math that is awash in metaphors, visual strategies, and quick tricks. It can be hard for a teacher to figure out which contexts and strategies will provide students with the best foundation for a conceptual understanding of integers. Specifically, some of the metaphors for integer addition become quite confusing when they are used to explain integer subtraction.

Personally, I have always felt like I get my students about 80% of the way there with my various analogies and number line strategies, but I’ve never finished an integer unit with the feeling that I had nailed it. I am hoping that by deeply investigating integers, I will find something useful to use in my own classroom.

But first: The four major contexts I have found for teaching integers.

Elevation

Elevation problems often place the student in the mind of a rock climber, scaling cliffs that stretch from deep canyons below sea level to high altitudes. Other elevation problems discuss submarines diving beneath the sea and helicopters rising up above the ocean. At other times, students are asked to compare the heights of various mountains with the depths of various ravines and trenches.

One particularly evocative elevation context involves a hot air balloon basket that is held up by balloons and weighed down by sandbags. If the balloons and sandbags equal each other, the basket remains at its baseline height (zero, for the purposes of the problem). Adding a balloon causes the basket to rise one foot, while adding a sandbag causes the basket to fall one foot. Removing a balloon causes the basket to fall, while removing a sandbag causes the basket to rise.

Temperature

Temperature is a common context that teacher use to introduce students to integers, in part because negative temperatures are some of the few negative numbers that students encounter outside of the math classroom. This prior knowledge is  less substantial in states like Alabama, where we are more used to temperatures with three digits than those with one. Regardless, most students have some prior knowledge about temperature and know that 23 degrees below 0 is colder than 8 degrees below 0.

Word problems involving temperature often discuss changes in the temperature from one time of day to another, or compare temperatures between cities to find how much colder one place is from another.

More abstractly, some teachers use the invented context of “hot and cold cubes” which are fictional cubes that either cause or lower the temperature of water by one degree. This context lends itself to student investigations with manipulatives.

Money

Money problems are common because their application to the real world is so strong and resonant. Every child has some prior knowledge about earning, spending, and owing money. Even though they may not have formal experience with debt, they are familiar enough with borrowing money from their parents to understand the idea.

Money is also useful because money can be earned and spent, and debts can be created and forgiven. These varied scenarios seem to provide a contextual support for many types of integer problems. Some teachers allow students to create a budget for themselves and keep track of the debits and credits to their savings over time.

Piles and Holes

James Tanton uses the metaphor of piles of sand and holes to teach integers. Piles represent positive numbers, while holes represent negative numbers. This image helps understand integer addition such as 5 + (-3), since every pile can be used to fill in a hole. Also, piles and holes can be removed, which can represent subtraction.

I have found a couple of examples of teachers using James’s analogy, but it definitely does not feel as widespread as the other three contexts. I include it because I think it would be valuable to compare the most common contexts with a context that is new to most people.

Other Contexts

I have found a couple of other contexts, such as “good things” and “bad things” or golf scores above and under par, which were less common or relied on more specific prior knowledge. I can’t imagine a lot of my students knowing much about how golf is scored, for example.

So there you have it! If you think of any other contexts that might be useful, please add them in the comments.