Most of us are old enough to remember the game Guess Who, right? It looked like this:

It went like this: You and an opponent each had a board in front of you that looked like this. Then you had a card with a face on it. So did your partner. By asking only questions that could be answered by “yes” or “no”, you needed to eliminate all the faces that were not on your opponent’s card in fewer turns than your opponent.

So you might ask “Does your person have glasses?” or “Is your person wearing a hat?” Based on the answered, you could flip some faces down because you knew they couldn’t be correct.

Okay. Now apply that to math. Imagine instead of human faces, it’s parabolas.

They also have one for lines, hexagons, rational functions, quadrilaterals (both basic and advanced).

Still yes or no questions. Students still have to determine which pictures to eliminate based on the answer to the yes or no questions. Set-up is incredibly easy.

As if that wasn’t cool enough, if you can think of a set of pictures you’d like to see, you can create your own Polygraph activity.

I thought it would be cool if there was one for systems of linear functions.

If you haven’t taken the time to explore Desmos yet, I’d say it’s about time.

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I used Desmos for the sum of two sine waves if different but close frequencies. Dead easy !

https://howardat58.wordpress.com/2015/07/31/the-mathematics-of-harmonic-means-and-the-beat-frequency/