Playing Pool with Desmos

Desmos, Games

Desmos Pool Title Image

I saw a student playing pool on his phone the other day, and it inspired me to create something in Desmos. That, along with Matt Vaudrey’s maze post and an old putt putt golf Desmos activity led to this.

The Links:


My goal is for students to get more practice graphing lines with domain and range restrictions (always a challenge for my kids). In this game, the objective is to draw the path of the white ball hitting and sending another ball into a pocket. The 8 ball is not allowed to be touched.

I like this setup because there are many options for made shots. There is more than one “right” answer.

Pool Multi Equations

This also allows students to compare and present work because it isn’t the same presentation every time. Each student/group could have a different route to a solution. Speaking of sharing work, Cory Henwood provided a glimpse of an awesome strategy using Nearpod. Really great stuff.


When using the putt putt version of this game, my students tend to struggle quite a bit. It’s been challenging trying to figure out a proper way to launch the task. However, I recently tried to ramp the lesson by starting the students with Michael Fenton-esque mini challenges (thanks to Matt’s maze post).

Here’s an example:

Begin with a level 1 challenge.

Level 1 Challenge - Pool Post

Most of the students are able to get through this and build some confidence. The strugglers are usually able to work with a group member to clear misconceptions. On to level 2…

Level 2 Challenge - Pool Post

Slightly more challenging, but again, most students will be able to get through it and build more confidence. Finally, it’s time to launch the putt putt/pool table challenge.

Level 3 Challenge - Pool Post

Using this strategy helped a lot and allowed more students to truly access the task. It was still a struggle in the end (more suggestions welcome), but I was much more pleased with the results.

How can the pool table challenges be improved? Thanks in advance for your feedback.

Update 1/23/17:

Patty Stephens made an awesome improvement to make this more realistic:

“If you want to model it in Desmos, an absolute value function would make the incoming/outgoing angles equal if reflecting off a horizontal or vertical line. I think you could use sliders to make the vertex a moveable point that would change the path of the ball depending on where it strikes the side of the pool table.

Here’s a little mockup I did for the cue ball shot, but I haven’t added an equation for the ball’s path.