Desmos: Dot Capture Game

I created a silly little game for my Algebra 1 students several weeks ago. The motivation? Five-fold!

  • We’re a little weak with graphing lines. Some open-ended, Desmos-driven, instant-feedback style practice may help.
  • Domain and range? Yeah, not so much.
  • Inequalities? Haven’t done them justice. Yet. (Growth mindset, baby!)
  • Vertex form for quadratics? Still struggling.
  • We tried Des-man a few days before this game and found nothing but pain and frustration. Some could be attributed to me (in particular, a bungled launch of the activity), some to students’ lingering struggles (noted above), and most of the rest to the declining state of our netbook cart. (But they seemed so cool in 2009!)

At any rate, to get that bad taste out of my mouth and set the stage for greater success on the next Des-man go around, I created the Dot Capture Game. Here’s what you need:

  • Students (working in pairs)
  • Devices (we actually used 50% smartphones, 25% tablets, 25% laptops)
  • The world’s greatest, most beautiful graphing calculator

And of course, the handout:

Dot Capture Game


Getting Started

Give a brief intro—or none at all—and turn ’em loose. If your experience is anything like mine, you’ll find yourself the weaving in and out of some great (albeit trivially-inspired) conversations about slope, intercepts, point-slope form, domain, range, inequalities and shading, vertices, direction of opening, etc.

This is definitely not high-quality modeling stuff (it’s not even low-quality modeling stuff), but it proved a great way to engage students with meaningful (read: productive) practice on a variety of topics related to graphing.

Oh, and the winner in my class? Here you go:



Final Thoughts

After trying this out in Algebra 1, I thought I’d throw it at my Algebra 2 and Precalculus students to see what they would do with it. It turned out to be good practice in those settings as well. Before sharing with these followup classes, a quick tweak to the handout was in order. In my first class, several students lost their graphs and expressions after hitting a deadly combination of keys on their device, and only one or two had been keeping a shiny written record. So to protect against future heartache, I added a second page to the handout. Here’s what one of them looked like at the end of class:

2014-04-04 15.05.13



Here’s a sweet suggestion from Desmos:

Comments 4

  1. This looks like fun! I am wondering how precise you required students to be for intersection points. For example, if I want a restricted domain for a shape that has a parabola boundary, do I estimate its intersection with a second function or do I solve for the exact intersection? I guess I have the same question for the Desman activity as well. Thanks!

  2. stcarranza, thanks for the comment and questions! In terms of precision, I leave quite a bit of room for students. We do very little “solving” and a lot more visual tinkering/experimenting. Desmos is great at giving students quick feedback on their graphs, and graphical-guess-and-check is one of the more commonly used strategies on this particular activity. I have less experience with Desman, but when I’ve used it in class, I followed the same approach.

  3. Excellent activity. Thanks for sharing this idea and your worksheets. I have been amazed at how motivating this kind of activity can be for students, and I plan to use this with my Algebra students soon. We just looked at UCSMP’s “Square Grabber” to explore regression, so “dot capture” makes for a nice connection. Thanks!

  4. Hello, I was wondering if you had the URL to the winning graph? I am currently completing a math assignment where one of the components is to include a shaded region in my graph and I am unsure as to how to restrict the shading between two parabolas.

    Thank you!!

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