## Trying to find math inside everything else

### Trig without Trig

Over the summer I made a Donors Choose page in the hope of getting some clinometers, so that we can go out into the world and use them to calculate the heights of objects like trees and buildings. And we did!
I created the Clinometer Lab as an introduction to Trigonometry. As such, prior to the lab, they had not seen any trig at all. So I started off with this video as the homework from the night before.

In class, we talked about how, when the angle is the same, the ratio of the height and shadow is the same. And how, long ago, mathematicians made huge lists of all of these ratios.
So if they told me any angle, I could tell them the ratio, and then they could just set up the proportion and solve.

So we left the building and went to the park, armed with clinometers, measuring tape, calculators, and INBs, so do some calculations. I had the students get the angles from their eyes to the height of a tree, from two different spots, and the distances, so they could set up a proportion and discover the height of the tree. (When they finished, they did a nearby building. If they finished that too, the extension problem was to switch it up: given the height of a famous building, the Metlife Tower, that they could see from the park, and determine how far away they were.)

It went really well, and I think they got the idea. The fact that they could choose which tree to measure and were given free range of the park, and could choose where to stand to look at the top, but always had to come back to me to get their ratio, worked seamlessly. I could check in on them easily and keep them on the right path. (Especially with my co-teacher there to keep them all wrangled, or the AP who observed/helped chaperone the classes without my co-teacher.)

The next class, I revealed to them that I was not using that crazy chart to give them their ratio, but rather they can just get it themselves from the calculator, which basically internalized the list. Then they got it, that is was just ratios and proportions, not some crazy function thing.

Trig as a topic did not go great in my class, but that is the fault of my follow-up lesson, where I tried to squeeze in too much and didn’t do any practice, not that fault of this lesson, which still sticks in their minds. Later in the year we were doing a project about utilizing unused space, so we picked empty lots but couldn’t get in. So in order to figure out how big they were, we used clinometers, and trig. Now that’s a real world application.

### The Lab

Clinometer Lab Instructions

Clinometer Lab Sheet

### The Archimedes Lab

I love this lab, but I’m sure it can be improved, so I’d love to hear feedback in the comments.

When I was student teaching at Banana Kelly, they had a combined math/science program that often had many lab activities, both math labs and science labs. But I noticed the Systems of Equations unit didn’t really have a lab, so I set out to make one. I created the Archimedes lab because of that.

The story of Archimedes and the Crown of Syracuse says that he was able to determine that the crown was not pure gold by using mass and volume. We start by watching a short video about the story. (I had assigned the video as homework, but no one watched it. While my video homework watching rates aren’t stellar, they’ve never been this bad. I blame the fact that it’s been a while: the last video was in December.)

Then I tell them that we can do Archimedes one better. It’s been over 2000 years since he lived and we have algebra and precise tools on our side: we can figure out exactly how much gold was stolen, not just if some was.

To demonstrate this, we built several Mystery Blocks out of two different materials. Back at BK, we had lots of different materials in the science closet to use. Because the students would know the type of material (brass, aluminum, wood, etc) but not the size and shape, they would have to use density to solve the problem. (But I had seeded the story throughout the whole unit.) The density kit I requested last year never arrived, though, so I had to scrounge around for something, and I found the perfect thing: Cuisinaire Rods.

I noticed that, despite what I expected, the longer Cuisinaire rods are much less dense that the small single cubes. So I used some amount of cubes and some amount of rods to make the mystery blocks. Then I simply give the kids one cube, one rod, the block, a scale, and a ruler, and ask them to figure out how many if each kind are in the block.

This lab was much more procedural when I first made it, but I’ve embraced the problem-solving classroom since then. And while my students were unsure of what to do, I feel like we’ve built up to this kind of unstructured problem, and most of them took to it well.

When they thought they had a solution, I would press them on it. “Why do you think it’s 5 yellow blocks and 5 cubes?” If they responded that that matches up in size to the block, I would point out any others do also, like 4 yellow and 10 cubes. I would implore them to use the tools available to them. (We also talked about mass, volume, and density in the warm-up.) If they told me some combination gave them the right mass, I would point out that their volume would be off. If they told me no combination gave them the right volume AND right mass, I would ask why. Most would identify the tape/foil/wrapping paper as the culprit.

Most importantly, if they gave me a solution that was well supported, even if incorrect, I told them there was only one way to find out if they were right: unwrap the mystery block and see. The excitement at each table when they got to that point was palpable. One student said it felt like Christmas. If they were right, they were ecstatic. If they were not, they tried to figure out where they went wrong.

When I first made this lab, I put it at the end of the Systems unit, thinking they would need those tools. Now I have the confidence to put it at the beginning, and let them figure it out. No one used equations explicitly to solve the problem, but they definitely grappled with the idea that two separate constraints need to both be satisfied in order to solve a problem, which is an important understanding for systems.

This post is getting a little long, so I’ll probably split off into another posts with problems I had with the lesson, things that went well, and a call for suggestions. I just wanted to get this out there. It’s been a long time since I’ve blogged, because I’ve had a lot going on in my life. So I want to get back to it.

### The Lab Sheet

The Archimedes Lab

Accompanying Graph

### Dragonbox in the Classroom

Last week, my students spent 2 double periods playing Dragonbox, the iPad (and computer) game designed to teach solving linear equations, which I think it does quite well. (I agree with many of Max Ray’s opinions when he writes about it here. Which makes sense, as Max first showed me the game this past summer.)

While one of my goals was teaching solving equations, it was not my only one, which is what I wanted to talk about here. (I’ll probably review the game itself later.) I told the students that I had forgotten to make a lesson, so we were just going to play a game on the iPad today. What I did want, though, was for them to home their ability to figure out how something works. To me, this is an even more important lesson to get than just solving equations.

To this end, I talked about how websites like GameFAQs has walkthroughs for all sorts of games, but one walkthroughs were all written by regular players, who sat down with a game right when they bought it, took notes on what they did, figured things out, and shared with others. So we were going to take that role. In their Interactive Notebooks, I told them to write down every thing they could do in the game. Whenever they came across a new rule, some new ability, or a new solution to a tough puzzle, write it down. Example: “Tap the green swirl to make it disappear.”

The surprising part was, they really did it, and quite well. Hey even discovered a lot of things about the game that I didn’t know, because I always played it “perfectly,” since I knew the rules of algebra. (Example: if you have a denominator under a green swirl (aka 0) and tap it, the while thing disappears. Or a green swirl won’t disappear if it is the only thing left on its side, which was fun to talk about later.)

At the end of my first double, with about 20 minutes left, I compiled all the notes they took using Novel Ideas Only (where all students stand and share things they have written, only sitting once everything they have written down is said, either by themselves or someone else), creating a master list of actions they could refer to next time.

The next class, they came in and immediately started playing. I must say, the entire time I used it, the kids were really into it, and most of them were really persistent. Some occasionally requested help, but my intervention was minimal. This time, I had this answer several questions after they had played some more, which really dove into the meat of the game. What does this card or action in the game represent in math? Why does a certain rule in the game happen that way?

One thing I really loved is how solid the game got them on how dividing something by itself won’t make it go away. It was a tactic many of them tried in several levels and it always got them stuck. I focused on the difference between “zeroing out” and “oneing out.”

We had one major downside, technology-wise, though. Each game had four save files, which worked out, because I had four sections. So one file per student. But there is nothing to stop a student in one class from playing on, or, even worse, DELETING, another student’s file. I e-mailed the company, and they said a solution would happen in a future update.

Today was the follow-up quiz, and they mostly did well. The things they stuck on was something that wasn’t well covered in the game: the distributive property. But we’ll work on that.

### Steepest Stairs Redux

Last year I made a lesson about determining the steepest stairs, using pictures my co-teacher and I took and based on an idea from Dan Meyer. It took about a period, and was mostly teacher-led. But after arguments and deep thinking about slope, I wanted to go into the lesson deeper, so I turned it into a lab.

I started the same way, throwing up the (new and improved) opening slide and asking which they thought was the steepest and which was the shallowest.

I really like this new improved one because I took a picture of the toy staircase from the board game 13 Dead End Drive (middle left). Last time, there were overall agreement on the shallowest (the Holiday Market) while there was disagreement on steepest. This time, because the toy was tiny (if not shallow), we had some disagreement there, which really let us tease out some definitions of “steeper” and “shallower.”

Once we had definitions of steeper (which usually came out to something like “closer to vertical” or “at a bigger angle”), I handed out the pictures on a sheet of paper and asked them to develop a method for determine which was steeper, or the steepest. I mentioned coming up with some sort of “steepness grade” (because I thought it would be amusing to throw the word “grade” in there).

So I let them struggle, and come up with what information they had to ask me for, which I would then provide. If I had to do it again, I would also have pictures of the width of each stair, as a distracter, because some kids asked for it. Interestingly, some also asked for the angle, because of our prior experience in the year with the clinometers. I told them I didn’t have the clinometer with me at the time. One kid called me on it, because she knew I had a clinometer app on my iPad. So I told her (truthfully) some of the pictures were taken last year, before I had it.

So I had them come up with their own measures. If they tried to base it off of only height or only depth, I deflected with examples of really tall, really shallow stairs, or really short, really steep stairs.

By the end of the classes, students usually came up with one of three different measures: slope, the inverse of slope (depth over height), and grade (that is, slope as a percentage).

So they had to then reason as to why they might prefer height/depth to depth/over. (Their logic: it seems more natural to have bigger numbers be steeper stairs, rather than the other way around.) And so it was that point that I told them this “steepness” grade that they developed was often called “slope” by mathematicians.

At which point, I got a big “Ohhhhhhhhhhh.” Which always makes it worthwhile.

### The Materials

Stairs – Portrait

Stairs – Landscape

Steepest Stairs Lab

### Fish Populations and Proportions

One of the labs I did back at Banana Kelly was a fish population estimation lab. You may have seen something like it before elsewhere. The idea is to explore proportions and the mark and recapture technique of population estimation.

The gist is this: students have “lakes” filled with “fish” (boxes filled with lima beans). They use a sampling tool to collect a sample of fish and tag them all with stickers. Then they release the fish, mix them up, re-sample, and use proportions to determine the population of the lake. They do it a few times and average, then they count the actual population to see how close they were.

But I was at a BBQ the week before I did this lesson, and I was talking to my friend Rachel, who is a marine biologist. I mentioned the lab, and we talked about what they use tags for. One thing is to track populations over time, so they can determine the changes in populations since each different year has a different tag. I wondered if I could change the lab to include that.

(Rachel also dug up the video that I had students watch the night before. I’ve decide to have a little “flip” in my classroom by having students watch a video before we do a lab and start asking questions, which I can then address in the next class.)
So I thought about how I could change it. It actually took a lot of thinking, jotting things down on the white board, consulting with the living environment teacher to make sure I was on the right track. But I extended it, so now they would do at least 5 different calculations in the process, instead of spending all that time on just one proportion.

Now, students do the first part the same as before. Then, a random sample of fish “die” and are removed from the lake and put side, and a bunch of new fish are “born” by taking them from the bag of beans I had. Then when they took a sample of the new lake, they tagged the new fish (not already tagged) with a different color sticker. Now they had data from both years and could figure out the new population, and the difference from the old population.

Not every group got to the extension, but I think it improved the task overall.

### The Materials

Fish Lab Instructions (formatted to fit in an INB)

The Lab Report

### The Monty Hall Problem

(Step one in going through a bunch of posts I’ve wanted to make.)

After reading this post on the Monty Hall problem last year, I decided to do a lesson on it. And it worked out okay. But, as Riley Lark did in that post, I did it at the end of the probability unit. So this year, I decided to go for it and do it first. And I must say it worked out quite well, because from the get-go it shows them that what they think about probability isn’t quite right.

First, to play the game itself, it’s good to have a little showboat, plus something that is easy to reset. So I built this:

(It’s a display board and I cut the doors open.) So it was much easier to play the game from the stay, and to keep my hands hidden as I do things behind the doors.

The other thing I did was, before we discussed the theoretical solution, I had them experiment. I gave each pair of students 3 playing cards, 1 red (for the car) and 2 black (for the goats), so one player played host while the other switched or stayed.

The main thing to learn is you really need to MAKE them switch, because teenagers are stubborn and are sure they were right the first time. But only staying won’t show all the necessary results.

### Algebra Taboo

I remember reading about the idea of Math Taboo on Sam Shah’s blog, this post by Bowman Dickson. I feel like I had the idea independently, but it seems like many people have, by doing a cursory Google search of the phrase.

Unfortunately, there are lots of posts ABOUT math taboo, but no real materials provided. If I have seen anything, it’s a lesson plan on having the students make their own. Or I saw one for sale, but it was for the elementary level. So I made one myself.

My co-teacher and I went through all the Integrated Algebra regents given since 2008 and pulled out any words that it’s possible a student might not know. I also went through my own lessons and pulled out any vocabulary I had given them. Below is the .pdf for printing your own (I used card stock and laminated), and two .doc templates if you’d like to make more, or alter the ones I have. I made a total of 126 cards (63 double sides – maybe slightly overboard).

Since I found no others, it makes sense to share.

Math Taboo (full pdf)

Math Taboo Pink  Math Taboo Blue (doc template)

### 3 Acts – Potatoes

I tried this out today in class (and will repeat tomorrow), and it worked out quite well. So now I want to share, my first 3 Acts problem.

## Act 1

The question I intended to be asked was “How many of each potato do I need for the recipe?” or variants such as “What does he do now that the scale is broken?” or “Did he buy enough potatoes?” Those were all asked, along with some others.

## Act 2

The video shows some things (how many potatoes I bought the first time, and the cashier says the totals), but it’s easier to lay that out when the students ask.

After that, they also wanted to know how much the potatoes cost, so I provided that.

But that’s all the information I can give: my scale is broken and I didn’t take the receipts from the cashier. Luckily, this is enough.

## Act 3

After we calculated the weight, we compared when I weighed them in my “new” scale.

I wish I had my digital scale for a better Act 3, but it’s actually broken (and the calculations I had to do when it was inspired this problem) and the analog was cheaper. The solutions you calculate (.36 lb and .43 lb) are pretty close to the values on the scale (which I peg at .37 lb and .5 lb).

The problem itself, in terms of the system of equations involved, is not that complicated (because I am using it to introduce the concept of elimination), but for the students who solved it quickly, I had a trickier problem up my sleeve:

## Extension

What if I had bought 3 Idaho potatoes on the second trip? How can I figure out how much each one weighs now?

Potatoes.zip

### Steepest Stairs and Wacky Measurements

After reading Dan Meyer’s post mentioning a Steepest/Shallowest stairs contest, I decided to go for it. But Dan had them do it for homework after they knew what slope was. I decided that I thought steepness of stairs would be a great way to introduce the concept, and then we can have the contest after. So Ms. Barnett (my co-teacher) and I went around the area and took lots of pictures of stairs we can find. Then I put them up as a warm-up and asked them which were steepest and which were shallowest.

In every class, there was near-universal agreement on which stairs were the shallowest (the top-right), but lots of different votes for the steepest. So then I asked them, “How can you know? What does it mean to be steep?” I got a lot of good, intuitive answers from that (My favorite was that something is steeper when it is closer to being vertical). I asked them what they needed to know to find out which was steeper, and they said we should measure it.

But what exactly should we measure? That took a little cajoling and probing, until we eventually decided on the height of the step and how deep it was. So I gave it to them:

Alright, now we have these measurements, what can we do with them? I lead them on a discussion on how best to use these numbers (a ratio), and we looked at another example. This is a pretty clear example (1/2), but not all of them are. So we used our estimating skills.

And my personal favorite…

(They really asked if I had 11 cell phones. I guess my Photoshop skills are better than I thought.)

The best part of these pictures is that they so naturally prompted them to question the units of measurement. “That one is cell phones, but the other one is hands. How can we compare them?” And so it’s natural to talk about slope as a ratio with no units. I didn’t have to artificially insert it. I even had a picture of a curved slide at the end, so we could theorize about the steepness of that.

Finally at the end I mentioned the contest. Unfortunately, I’m afraid Ms. Barnett and I did too well finding stairs. I’ve had students say they’ve been looking, and some say they found some (but don’t have pictures yet, though they have one more week). I hope someone can knock us off our thrones:

## SLIDES:

Steep Stairs (PDF)

Steep Stairs (PPT)

### How to Lie with Statistics – Stations

I base my statistics unit on the book How to Lie with Statistics, by Darrell Huff, because I think it contains a lot of really important information that everyone should know to live their lives and to stop themselves being taken advantage of. (Which is one of the majors benefits of learning math, as it’s so easy for people who know math to swindle people who don’t.)

The problem is, though, all that important information that I think is so critical is not that important in the minds of the NY Board of Regents. Last year I went ahead and taught the whole unit around it anyway, but I’ve learned the errors of my ways when I found that my students were lacking in, say, the ability to make a box-and-whisker plot.

To compensate, I (along with my fabulous co-teacher) did a one-hour lesson that I broke up into stations, with each station representing a different “Lying Technique” that I wanted the students to learn about. (I had already covered The Sample with the Built-in Bias and The Well-Chosen Average as a normal lesson prior, because those are still relevant topics.) Each station lasted about 10 minutes, with some time for wrap-up and transit.

First page of Station 1

I also did this to support the project I had them working on, which is the topic of another post.

Stations in pdf form.