# Blermions, Cyclic Quadrilaterals, and Crossed Chords

Last year in Geometry, the other teacher and I weren’t pleased how we introduced the crossed chord theorem. Basically, we ran out of time to come up with a *great* idea and instead had kids measure some things, take the products, and see that the theorem held true. Not our style. We were doing the heavy lifting and kids were making the connection that was served up on a platter.

When we met last week, we decided to rectify this. We brainstormed some general ideas, and I turned those into this activity.

The setup: Kids are so used to looking at “normal” quadrilaterals in geometry. So we thought we’d exploit that. We don’t mention circles. We don’t mention chords.

The TL;DR version: students investigate all quadrilaterals where the diagonals satisfy the property that ac=bd. Students are guided to make a conjecture which we as teachers know will be wrong. Then we show a counter-example to blow their conjecture up. And them bam: they have to try again. Using geogebra and some more encouragement, students discover that all cyclic quadrilaterals satisfy ac=bd. And so the circle emerges out of this investigation of quadrilaterals and diagonals. This is, then, the crossed chord theorem. Which students got at by investigating quadrilaterals. Weird. Now they are in a prime place for wondering why the circle shows up. Proof time!

Here’s the start: we introduce a new type of quadrilateral called a “blermion.” (.docx here)

We had some debate over whether we were giving too much away with this start [1], but we decided we weren’t. (We’re going backwards. The students aren’t deriving the formula. They’re using the formula (which we are calling a “property” of quadrilaterals) to come up with the circle part of the theorem.)

So yeah, we gave kids the ac=bd formula, but in relation to the diagonals of quadrilaterals. And we asked: “which quadrilaterals will this property hold for? We’ll call ’em blermions”

So I ask them to look at the standard quadrilaterals they know — investigating this property using a geogebra sheet — and having them making a conjecture about blermions.

The ggb sheet is here.

So students play on geogebra and come up with some understandings (inductively) about which quadrilaterals are blermions. Then they make a conjecture about all blermions.

This conjecture will fail. Because it is based on students only looking at “nice” quadrilaterals. I want the conjecture to fail. I want to emphasize the point that looking at “nice” examples can often lead to blind spots in your logic.

Students will see it fail when they are asked to drag the four points to specific places (see #5 below). The quadrilateral that results is weird looking. There is nothing that seems special about it. But it does have ac=bd. It is a blermion. Their conjecture about blermions was wrong!

Now students are sent on a chase to find more blermions — and they are encouraged to not just look at “nice” quadrilaterals. They record their results. (If they are stuck, a teacher can have the students fix three points and only drag the fourth point; It turns out you will always be able to drag that point to have ac=bd… and that in fact you can find an infinite number of additional points by doing this dragging of that fourth point.)

At this point, once they have found lots of blermions, students are going to try to make another conjecture about all blermions. I wonder if any student is going to get it. It’s okay if they don’t. At this point, I’m going to have every student plot a different blermion (some “nice” quadrilaterals, but mostly not nice ones). Then I’m going to have them pick any three points and change the color of them. Finally, I’m going to have students go to the “draw a circle with three points” tool, and be surprised by the fact that the circle always goes through that fourth uncolored point.

Why is this good? I hope they don’t get it. Because seeing that every blermion works like this (a circle goes through all four vertices of the blermion) is the key wow factor for kids. It’s strange, because even though I will be giving away this key fact, I think all this play will make this key fact interesting and weird. [2] Once they all see that, they are going to be curious as to how circles even got involved with these quadrilaterals in the first place. And… that is perfect… because then the kids are going to want to know why this happened.

And then we can transition to figuring out how to prove this. Because suddenly the crossed chord theorem is weird and strange and unexpected, and suddenly we kinda want to know why it works!

[1] We had to decide whether students should discover the property ac=bd for crossed chords. Motivating that from a circle and crossed chords was hard. We needed kids to somehow see similar triangles (which felt like we would be giving away too much) or come up with the multiplication idea of the pieces of chords on their own. We had ways to motivate that multiplication, but they weren’t elegant. So we scrapped that.

[2] Here’s the thing. Most things in geometry are presented to students in such a way that their wonderment about the geometric thing is killed. In a proof, the statement to be proved is given up front — and suddenly it isn’t interesting. It might be something really cool, but the exercise around doing the proof doesn’t highlight that. Or — as I’ve blogged before — theorems like the ones involving all the triangle centers… we tell kids to plot the perpendicular bisectors of all three sides of a triangle and they meet at a single point. It isn’t strange and wonderful. They don’t see why that’s weird. They just know we told them to plot the perpendicular bisectors, and they know something will happen because why else would we have them do it? We kill the wonderment of geometry in so many ways.

I want the weirdness and unexpected and unintuitiveness to come back to geometry… that’s where the beauty and curiosity are… and only then have my students work on figuring out why the unexpected happens… and get to the point where the weird and unexpected and unintuitive become obvious and natural. Making the unnatural natural. Yup, that’s the goal. But to do that, you have to first get to the unnatural.

# The betterQs blog: A new #MTBoS adventure

For the past few years, I’ve been (sometimes daily, sometimes sporadically) posting on the one good thing blog. Last year I did it every single day. Often times it was a short post, especially in tough days where it was hard to find some little nugget. But what I loved was that it made me reflect consciously on joy and goodness, and pay attention to it. [1]

This year I want to spend some time thinking about how to question well. More specifically, thinking intentionally about what questioning looks like (and how it can be improved) in my classroom — both on my end and on my students’ end. I thought I would blog about it throughout the year, and figured it would be fun to blog with others. @rdkpickle had the same idea! So we figured it was a good idea, and set up a collaborative blog. All this is to say:

But more importantly…You are warmly and heartily welcome to join us, and become an author. The blog just started and we’d love to get as many voices and experiences going on the ground floor.

Read a few posts. Browse a bit. It’s only a few days old, so there isn’t too much to gander at! And consider joining us. (If you want, there’s a tab at the top of the blog that tells you how to join, or just click here. We’ll add you as an official author!)

“But Sam,” you say, “I don’t have time to write every day…”

Silly goose, I respond! You can write however frequently works for you. Once a week? Once a month? Three times a year? The point is to take some time — however much of it — to think about questioning in your classroom.

“But Sam,” you say, “I don’t have a lot to write about…”

Silly turkey, I shoot back! I think it would be cool if you even wrote down a single question that you really loved asking because it provoked discussion. No need to deeply analyze it if you don’t want! Maybe a teacher reading the blog will read that question and think: “YAS! THIS IS EXACTLY THE QUESTION I NEEDED!” And if there were a lot of people just throwing down their good thought-provoking questions, we would soon have an amazing repository.

“But Sam,” you say, “I have a blog of my own! Why don’t I just post it there?”

Silly quail, I reply! You can post anything to do with questioning both on your own blog, and on this blog. No rule against that! In fact, I did that for my first post on the betterQs blog. And that way, someone reading the betterQs blog might get to know you and your own blog!

“But Sam,” you say, “I’m still scared… I don’t want to sign up and then not do it.”

Silly emu, I say. Why not take a baby step and just commit yourself to writing one or two things? Just keep a lookout in your school about how you question, or try to script a good question and see how it goes in your classroom, or rewrite a test question and explain how you rewrote it and why… Baby emu steps. And just see how it goes! You just might think: hey, questioning is something I want to pay just a bit more attention to!

Or, silly emu, don’t worry about signing up! As I wrote a couple years ago: “You should never feel guilty engaging with the community in ways that make sense to you. We’re all coming at teaching from such different places in our careers, such different backgrounds, and such different environments. We all need and want different things.” In other words, you do you.

[1] I also love the fact that because I’ve been using the blog semi-regularly, I can see an archive of so many good things of my own (in addition to seeing everyone else’s good things). On down days, it really helps me remember I’m not as bad as my brain tries to convince me I am.

# Northwestern’s Distinguished Secondary Teacher Award

I don’t know why I wasn’t going to post about this… but today I decided I would do a short write-up of it because I blog to archive my teaching, and this was a really wonderful thing that needs to be archived. This summer I was one of five teachers who received Northwestern’s Distinguished Secondary Teacher Award. I think partly the reason I didn’t post it is because I suffer from imposter syndrome, and felt like I wasn’t worthy… but I need to get over that thinking.

A former student who was a senior graduating from Northwestern nominated me by writing a reflection about her experience in our calculus class. I then was asked to submit some letters of recommendation and a teaching philosophy / personal statement, which I did. I actually wasn’t going to — another thing on my plate! — but I started thinking how lucky I was to have a former student take the time to write something up about me, and I figured I could put in a couple hours of work to honor that. A few months later, I received an email saying I was a semi-finalist, and had to do a 1 hour video conference interview with six people (administrators, professors, and students at Northwestern) — and that video was then shared with the whole selection committee. Scary!!! I did it, but was a rambling nervous fool. And then: I got a call telling me I was selected, and that I was going to be attending Northwestern’s graduation and be feted.

I was super excited that I got to invite my family (we turned it into a mini-family vacation to Chicago) and a teacher colleague/friend/mentor to join me. This was my favorite photo from the weekend: it was me and my family, my teacher friend, and my former student who nominated me and her family.

The experience… it was once-in-a-lifetime. Memorable moments?

• They put me and my parents up in two “executive suites” at the four seasons. The amount of fanciness was unbelievable, and the view of Lake Michigan from my room was stunning. They put little slippers by your bed each night! I doubt I’ll ever be at a place in my life where I’ll get to experience that kind of luxury again.
• There was a luncheon on the first day where the award winners and students (and their families) all got to meet, and the students read aloud their nomination letter (which I had not been shown). I got teary when mine was read. And then I had to give a mini-3 minute speech which I was terrified to do but I think it went well.
• I got to see my former student win an award!
• There was a fancy fancy dinner for long-term retiring faculty and the award winners (where we were again feted), and I got to hear those receiving honorary doctorates give mini-speeches. My favorite was Dan Shechtman who is a Nobel prize winning chemist who talked about teaching young kids about science and not underestimating their abilities.
• Graduation! They had the award winners sit at the front of the stage and we were called out during the ceremony. I was sitting next to the president of the university. This was my view:
When they called out our names during the program, and there was a wave of applause and cheers, I got chills. In a good way.
• We (my parents and me) went to my former student’s apartment for lunch with her family. We had falafel delivered and talked about … well, everything. Those two hours were my favorite, actually, of the entire weekend. Except for putting on those four season slippers!
• I was invited to go to the “mini-graduation” for the School of Social Policy to see my former student get called on stage and graduate. (But then I was told I was sitting on stage, front and center.) It was so exciting when her name was called that I snuck out my phone to try to get a good photo of it happening!
I secretly was relieved when my name wasn’t called and I wasn’t called out… too much fete-ing can be exhausting!… but right at the end of the ceremony they had awards they were handing out to professors and they then called me out and gave me a plaque with my name inscribed on it. So I suppose I couldn’t avoid betting fete-ed after all. :)

It was an unbelievable experience. For me, the most wonderful part of this adventure was knowing it was all kicked off by a former student — and that I got to share in an important turning point in her life.

# Everyone Has To Raise Their Hands… and other thoughts

We haven’t started school year. But last week and this week I’ve done some brainstorming about things I intend to do this school year (which *ahem* has some aphorism involving a road and hell associated with it, right?), and so I thought I’d pull out those few concrete little bits that deal with questioning that I want to do this year.

1. If your group has a question, everyone in the group must raise their hand to call me over… This is how I started the last couple years of precalculus (all my kids work in groups). The idea was that if a kid had a question, they needed to first talk with their group so that the math teacher (me!) was not the sole mathematical authority in the classroom. I quickly added on … and I will call on one of you randomly to ask me the question. That way everyone in the group had to be comfortable asking the question, and that it was a real group question and not just an individual question.Last year, for some reason, I didn’t keep up with this practice, and started answering individual questions. I need to remember to keep up with this practice, because it’s awesome  and it works to get kids really talking and explaining without you.
2. I taught calculus for seven years, and when I started standards based grading, I used to put after each question testing each skill a little box:
It was useful when I met with students to discuss their tests. If they felt shaky and did poorly, that meant one thing to me. If they felt confident and did poorly, that meant another. If they felt shaky and did awesome, that meant something totally different. It led to some good conversations, and got kids to be more meta-cognitive. It also led to some interesting written feedback on the tests (even if I didn’t meet with the student).But I only ever did that in calculus, and I don’t teach calculus anymore. So I want to incorporate this on my assessments in my other classes — at least geometry and precalculus. When I’m asking a “mathy” question, this is a sort of different additional question that helps me put their response in some context.
3. Questions can have different purposes for me, even though I don’t (in the moment) think of them this way. Mostly they are to either (a) to get a student to go from a place of not understand to understanding (through asking questions to get them to think and make connections), or they are (b) to help me understand what a kid (or my class as a whole) is understanding.If I’m asking a question to the whole class, and my purpose is to figure out what my kids understand and what they don’t, I’m not going to have my kids raise their hands anymore. I got to the point where sometimes I would call on kids with their hands raised, and sometimes not. I mean: if the kids all raising their hands to answer a question feel they know the answer, then why am I calling on them? Instead, I am thinking of stealing an idea from a friend who taught middle school: THE POPSICLE STICKS OF DESTINY. I am going to have my kids’ names written down on popsicle sticks and pull them out of a mason jar (because I’m such a hipster!) to randomly call on someone. Yeah, index cards work too, but INDEX CARDS OF DESTINY is way less fun to say dramatically.

If I do this, however, I need to make sure that the kid who doesn’t know something or is confused feels like the classroom is a safe space. This year I’ll be teaching the advanced sections, so there is a lot of insecurity that these kids have about “being smart” (*cringe* I hate that word) and “appearing dumb” to their classmates. I have to brainstorm how I’m going to publicly reward kids for having good questions or being confused but doing something about that confusion or for being wrong but for owning it and saying “I NEED TO GET THINGS WRONG IN ORDER TO FIGURE OUT HOW TO BE RIGHT. AND I’M AWESOME FOR KNOWING THAT.” Heck, maybe I’ll have a poster made which says that, and have kids read it aloud occasionally when they’re wrong. And I should point to it and say it when I am wrong. Or maybe that’s dumb. I don’t know.

That’s about it for now. Hopefully more to come as I figure things out!

[cross posted on the betterQs blog!]

# My Thoughts about the Evolution of the #MTBoS: 2015 edition

Twitter Math Camp just ended, and I’m feeling a sense of sadness because I miss my friends already, but that is counterbalanced by renewed invigoration. Although I’m not ready to return to the classroom yet, the reason is because now I have so many things I want to think about and implement, and I need time to sort all of that out.

## A Change Was A Brewin’

But while we were all together, something started occurring to me. I do a lot of thinking about this online community, the #MTBoS… who we are, why we came together, why we continue to come together, how are we inviting those who want to join in the fun, what we can do as a collective whole, and what we are doing as a collective whole. For me, this community started 8 years ago, and I’ve seen it grow from a nascent group of bloggers who shared their classroom activities and musings on education and their kids to a much more complex *thingie.* (Yup, I’m awesome at wording, right?!) Two years ago, after TMC13, I wrote:

the main takeaway of the conference was new. It was that we are a powerful force. We are not a loosely connected network of professionals, but we are a growing, tightly-connected network of professionals engaged in something unbelievably awesome. Through this community, we are all – in our own ways – becoming teacher leaders.

Around that time, I saw a lot of cool collaborative *thingies* just starting to bloom and blogged about how frakking awesome that was:

One thing that is now crystal clear to me is that we’re shifting into a new phase. (“We’re” meaning our little math teacher online community.)[…] Now in the past year or year and a half, there has been an explosion of activity. and this explosion seems to center around (a) collaboration and generating things which are (b) not really centered about us and our individual classrooms. We’re thinking bigger than ourselves.

I’m talking the letters to the first year teachers, I’m talking the Global Math Department, I’m talking thevisualpatterns website, I’m talking the month long new blogger initiation, I’m talking the freaking inspirational One Good Thing group blog, I’m talking Math Munch, I’m talking the collaborative blog Math Mistakes, I’m talking MathRecap to share good math PD/talks with each other. And of course, now we have the Productive Struggle blog, Daily Desmos, and the Infinite Tangents podcast. [1]

We’re still keeping our blogs, and archiving our teaching and sharing ideas, and talking on twitter. But now we’re also moving into creating these other things which are crowdsourced and for people other than just those in our little community…

It’s been a freakin’ pleasure to see all this stuff emerge out of the fertile soil that we already had. We’re starting to create something new and different… and… and… I can’t wait to see what happens.

At that time, it was just the beginning… So much has happened since.

## We’re at Someplace New

There are many more people who are jumping in. More initiatives and collaborative projects are happening. People are meeting up more and more in real life tweetups. There has been an NPR story on one of us. Multiple grad students are doing their dissertation and research about our community. The MTBoS has no official organization or centralized structure and doesn’t speak with a single voice (something I value greatly), but it has gotten the attention of the National Council for Teachers of Mathematics (NCTM). The president elect and the executive director of NCTM came to TMC15. They have given us booth space at their last national conference. There are a series of sessions at MTBoS (strands) that have happened (one, two).  It’s worth thinking about what this means.

When I was at TMC15, I noticed that there wasn’t as many conversations or mentions of “celebrities” or “rockstars” as in previous years. I think I heard those words at most twice. It’s not like people weren’t excited to meet their math teacher crushes, but something felt different. I think we’re shifting away from “celebrities” and “rockstars” and are moving towards brands. Okay, that’s not the perfect term, because there is something pejorative about that, and I mean anything but that, but people have their *thingies.*

Some quick examples:

@cheesemonkeysf is known for talking points and how the social-emotional life of a student has everything to do with their ability to learn

@PiSpeak is known for math debate in the classroom

@sophgermain is known for diversity and inclusion issues

@fawnpnguyen is known for visual patterns and her Sage Experienced Teacher Wisdom (aka her funny and emotionally charged stories from her classroom)

@mathequalslove is known for her work on interactive notebooks and her craftiness

@AlexOverwijk is known for activity based teaching

@mpershan is known for exploiting math mistakes and encouraging critical discourse

and the list can go on and on and on…

I think the idea of “celebrity” is being replaced with “brand” (or niche, or whatever). As the community grows, there are more and more voices. But there are certain ones that get a lot of traction. Of course the more involved they are (via blogging or tweeting), the more noticed they are. But that’s not enough. It’s their messages.

One came from Christopher Danielson’s amazing keynote at the conference. His message: “Find what you love. Do more of that.” Of course, that’s a little pat, and you need to see the whole presentation to truly understand. It isn’t “I love mathematics” or “I love kids.” He asked us to dig deeper, go a bit farther. What about mathematics speaks to us? What about working with kids makes us tick? His example: he loves ambiguity. The space between the certainties. And so a lot of his work as a teacher is exploiting those ambiguities with his students to get them to learn mathematics — but also hopefully appreciate (and dare I say, love) ambiguity too?

The other is from a reddit AMA conversation with Kenji Lopez-Alt. He writes the best food blog posts evar! And in this Ask Me Anything, he was asked for advice on starting a food blog:

I’m not posting this because I want to share his advice on starting and maintaining a blog. But I realized why I love his posts is because he does have a specific point of view, and that point of view speaks to me in spades. His passion about the science of foods and sharing his discoveries with others is so apparent. But I suppose what I mean is: he has found something he loves, and is doing more of that. He has a brand.

I suppose I’m saying that what I’m seeing is that there are a lot of others out there in the math community who have found that thing they love, that specific thing that makes them the teacher they are, the thing they are passionate about, and their blog and twitter conversations tend to revolve around that. They are doing what Kenji suggested — but I’m guessing without even consciously realizing it.

I don’t know, I’m just musing here. But I think ages ago there were “rockstars” and “celebrities” who were well-known — but some of their rockstarness was from being around for a long time and thus having a large network of people they could communicate with in a tightly knit community that was growing. Now I think that may be shifting. I think as we have more people, the MTBoS has a lot of mini-communities that exist within it — it’s a patchwork quilt. And that is a natural and good thing.

And I’m seeing specific people — old and new — speaking with clear voices and messages. This is what I’m passionate about. This is how I enact that passion. This is what I stand for. This is my brand. Hear me roar. [1]

And they are going outside of their schools and our smaller community to bring the thing they love to a larger audience. Creating websites, writing books, leading professional development, etc. They are expanding their brand. (And again, I don’t mean brand in a negative way!)

These are the people that speak to me. They have a voice. And I’m interested in hearing what that voice is saying. I would venture to say that they speak to others for that same reason.

What is so awesome sauce about this is that they are becoming teacher leaders. We don’t have models for what a teacher leader is in the United States. Once you become a teacher, unless you leave the classroom, you will always be a teacher. There are no ranks (except maybe the very expensive National Board certification), and there aren’t well-defined pathways to get more involved in the profession — again, without leaving the classroom. There aren’t a lot of models of those who are effecting change outside their own classroom. Think about it: excluding the MTBoS, can you think of five teacher leaders who are still in the classroom? One? [2]

But I see right now in this community the creation of new models for what a teacher leader can look like. Whether you have five years in the classroom or twenty five, there are pathways that people in the MTBoS are carving out in order to share what they love.  Help other teachers. Impact student lives. And more than anything, this is what I predict will be happening more and more as the community continues to grow and mature. [3]

## Back To Me

On a more personal reflective note, I realized I don’t think I have that brand. I think if 10 people were asked in the MTBoS, “what is Sam Shah about?” I doubt there would be a general consensus. Why? Because I don’t think I have figured that out for myself… yet. I know many things about myself as a teacher — I can be reflective as heck at times — but I still don’t think I speak with that voice or brand that so many others I admire do. And that’s not a bad thing at all. It’s just me still figuring stuff out.

[1] Again, I don’t think many would even say they’re aware of it…

[2] This is not a knock on those who have left the classroom to help our profession. I am just saying it’s hard to be a teacher leader and stay in the classroom. And I want to stay in the classroom.

[3] A lot of this part of my thinking came from @pegcagle and @_levi_’s TMC talk.

# Taking Stock

I spent 5 hours today cleaning out my desk, going through files, recycling mountains of paper. In concrete terms, it means school is over. Graduation is tomorrow. And then: I’m on summer vacation [1]. So now a bit of a brain dump as I take stock.

I’ve found this year to be an important transition point:

For the first time, I taught ninth graders, and for the first time, I taught geometry. And in order to do that, I worked an insane number of hours with my partner-in-crime and co-teacher BK in order to write an entire curriculum from scratch, from head to toe. Yup, you read that right. We — in essence — wrote a textbook. We sequenced the course, we wrote materials and designed activities for the course, and we had kids do all the heavy lifting. There are particular moments as a teacher which standout as “big moments.” Moments where we know we’ve developed immensely as a teacher. Transitioning from individual and partner work into total groupwork was one of those moments. Converting my non-AP calculus course into a standards based grading course was one of those moments. And writing a curriculum from scratch, in a single year, with an insanely thoughtful collaborator was the most recent of those moments [2].

The previous two years (before this school year) were two of the hardest years I’ve had as a teacher. We teachers were called on to do a lot in the wake of our school’s five year strategic plan — and it became overwhelming. I had no work-life balance. And  I became a bit curmudgeonly because of those tough years. But this year, things have been better. I still have no work-life balance, but the overwhelming onslaught of initiatives have subsided. One of the things I did to actively try to stay positive this year was to write down every single day one good thing that happened to me — big or small. From the first day of classes to the last. And those things are archived here. This was especially important because at the start of the school year, my mom was diagnosed with cancer (she is doing very well, fyi, no worries).

That being said, I am going to make a goal: that next year, I am going to just let the things that I can’t control go… There’s no point in getting worked up over something that you can’t do anything about. Instead, I’m going to stay loose, and bring back my frivolity and humor, and go off the beaten path in class more. While organizing today, I was looking through a number of old emails and cards from students, and saw so many inside jokes and fun times that they references… and then I thought about this year… and I came up blank. I couldn’t think of a time that I doubled over laughing in class. I couldn’t think of an ongoing joke that I had with a student. I could think of great lessons and a ha moments, but nothing frivolous and fun. So my vow is to make sure that next year involves more joy and laughter. For me, and for my studentsEvery day.

Wow, yes, this braindump led me to something big. With that, I’m out.

[1] That doesn’t mean I’m done with school. I have lucky 13 college recommendations to write. And two summer projects that each will take 25 hours each to complete (revise my multivariable calculus curriculum; plan for our new schedule next year with longer blocks).

[2] I’ve written entire course curricula before. Calculus, for example. But that took a few years to write and get added to. And Adv. Precalculus, which I did in a single year, but lacked the collaboration and innovation that I was able to do this year with BK.

# Multivariable Calculus Projects 2014-2015

At the end of each year in Multivariable Calculus, I have students develop and execute their own “final project.” It’s fairly open-ended and students end up finding something they are personally interested/invested in and they go for it.

This year I had six students and these are their projects.

“Exploring the Normal Distribution Through the Box-Muller Transform and Visualizing It Using Computer Science” (GT)

This student had never taken a statistics course but was interested in that. We also talked about how to find the area under the normal distribution using multivariable calculus (and showed it was 1). Armed with those two things, this student who likes computer science found a way to pick independently two numbers (one each from two uniform distributions), and have them undergo a few transformations involving square roots and sine/cosines, and then those two numbers would generate two new numbers. Doing this a bunch of times will create a whole pile of new numbers, and it turns out that those square roots and sine/cosines somehow create a bunch of numbers that exactly follow a normal distribution. So weird. So cool.

“XRayField: Detecting Minecraft Cheating using Physics and Calculus” (W.M.)

This student loves Minecraft and hosts a Minecraft server where tons of kids at our school play. Earlier in the year, there was a big scandal because there were people cheating when playing on this server — using modifications to give themselves additional advantages. (This was even chronicled by the school newspaper.) One of the modifications allows players to see where the diamonds are hidden, so they can dig right to them. So this student who runs the server wanted to find a way to detect cheaters. So he created a force field around each diamond (using the inverse square law in 3D), and then essentially calculated the work done by the force field on the motion of a player. A player moving directly with the force field (like on the left in the image above) will get a higher “work score” than someone on the right (which is moving sometimes with the forcefield, sometimes not). In other words, he’s calculating a line integral in a field. His data was impressive. He had some students cheat to see what would happen, and others not. And in this process, he even caught a cheater who had been cheating undetected. Honestly, this might be one of my favorite projects of all time because of how unique it was, and how perfectly it fit in with the course.

“Space Filling Curves” (L.S.)

This student with a more artistic bent was interested by “Space Filling Curves” (we saw some of them when I started talking about parametric curves in three dimensions, and we fiddled around with Lissajous curves to end up with some space filling curves). This student created three art pieces. The first was a 2D Hilbert curve which is space filling. The second was a 3D Hilbert curve which is space filling (pictured above). The third was writing a computer program to actually generate (live) a space filling curve which involves a parametrically defined curve, where each of the x(t) and y(t) equations involved an infinite sum (where each term in this infinite sum was reliant on this other weird piecewise and periodic function). I wish I had a video showing this program execute in real time, and how it graphed for us — live — a curve which was drawing itself and how that curve being drawn truly filled space. It blew my mind.

“The Math Is Right: The Math Behind Game Shows” (J.S.)

This student, since a young age, loved watching the Game Show Network with his mother. So for his final project, he wanted to analyze game shows — specifically Deal or No Deal, and the big wheel in the Price is Right. I had never thought deeply about the mathematics of both, but he addressed the question: “When should you take the deal? Is there an optimal time to do so?” (with Deal or No Deal) and “If you’re the second player spinning the big wheel (out of three players), how do you decide whether to spin a second time or not?” (for the Price is Right). As I saw him work through this project — especially the Price is Right problem — I saw so much rich mathematics unfold, involving generating functions, combining distributions, and simulating. It’s a deceptively simple question, with a beautifully rich analysis that hides behind it. And that can be extended in so many ways.

“The Art of Balance” (M.S.)

This photograph may make it look like the books are touching the wine holder. That is not the case. This wine holder is standing up — quite robustly as we tested — through it’s own volition. And — importantly — because the student who built it understood the principle behind the center of mass. This student’s project started out with him analyzing the “book stacking problem” (which involves how much “overhang” you can create while stacking books at the edge of the table. For example, with one book, you can put it halfway over the table and it will not fall. It turns out that you can actually get infinite overhang… you just need a lot of books. This analysis centered around the center of mass of these books, and actually had this student construct a giant tower of books. The second part of this project involved the creation of this wine holder, which was initially conceived of mathematically using center of mass, then that got complicated so the student started playing around with torque which got more complicated, so the student eventually used intuition and guess and check (based on his general understanding of center of mass). Finally he got it to work. The one thing this student wanted to do for his project was “build/create something” and he did!

“Visualizing Calculus” (T.J.)

This student wanted to make visualizations of some of the things we’ve learned about this year. So he took it upon himself to learn some of the code needed to make Wolfram Demonstrations, and then went forth to do it. He first was fascinated with the idea of fractional derivatives, so he made a visualization of that. Then he wanted to illustrate the idea of the gradient and how the gradient of a 2D surface in 3D space sort of defined a plane tangent to the surface if you zoomed in enough. Finally, he created an applet where the user enters a 2D vector field, and then it calculates the divergence and curl at every point of the vector field. His description for what the divergence was was interesting, and new to me. About the point chosen on the applet, he drew a circle (and the vector field was illustrated in the background). He said “imagine you have a light sprinkling of sand on this whole x-y plane… and then wind started pushing it around — where the wind is represented by the vector field, so the direction and strength of the wind is determined by the vector field. If more sand is coming into the circle and leaving it, then the divergence is negative, if more sand is leaving the circle than coming into it, then the divergence is positive, and if equal amounts of sand are coming in and leaving the circle, then the divergence is zero.”