A cool thing happened in Algebra 1 today. We’ve been working our way through an “Applications of Quadratics” unit (one that needs a healthy dose of revision in the near future). Today: projectile-motion problems.

The basic flow for each scenario:

• Set the context (catapult, arrow, ball from roof, etc.)
• Substitute an input, evaluate, explain the result in context
• Substitute an output, solve, explain the result in the context

One student was struggling with the two-solution result to bullet #3 above. “How could there be two answers?”

I’ve been asked this question before, and feel like I’ve been able to help students reasonably well with a combination of questioning, hand-waving, sketching, etc.

But today? I reached into my pocket and added one more element to the conversation:

Now, I love using Desmos on a laptop. Nothing beats that graphing experience in my mind. But to have a functional version of Desmos sitting in my pocket, ready to bring into a conversation at a moment’s notice… That’s cool.