## Thursday, May 5, 2016

### Guess Again

Graham Fletcher was tweeting from a Marian Small presentation this morning.

I think the theme was number sense activities. These line questions caught my interest so I wanted to make a GeoGebra version. This post is about how I made it. I'm always torn about these things because so much of the good math is in making them, but I'm mostly making them for students. But learning how to make in GeoGebra is often not something that is  engaging to a majority of them...

If you want to try it first, it's on GeoGebraTube.

First thought: Pick a random value - maybe  1 to 100? - and a smaller value, then have students guess a higher value. (Basically Marian's second photo.) Should it just be multiples of 5? I liked the idea of multiples, so I randomly pick a scale from 1 to 5, then pick a value 1 to 30 for a central value. Pick a number lower and higher, and the setup is done.

Steve Phelps was playing with GeoGebra color the other day, so I added the unnecessary frill of different colors, but it makes it a little cooler to me. Replaying it, I realized it would definitely be better if different points were unknown, so the sketch randomly selects the low, medium or high point for guessing.

A GeoGebra fine point. If you have the values randomly determined directly, then anything that makes the sketch recompute changes the value. So I have variables set randomly, but just assign those values to game values when the New button is pressed using the SetValue command. The guesses count also uses the SetValue command: SetValue[numguess, numguess+1] everytime the guess value changes.

Then it's just bells & whistles using the condition to show object on the Advance tab. A random element of {1,2,3} is picked to hide a value, which shows if guess == value. Some different text

The "Within..." is probably the sketchiest part. I want some further information, but not perfect, so it randomly assigns a number up to two times how far away you are.

There's a bit of oddness from uploading to GeoGebraTube in terms of scaling, so I had to ask users to hit the button to start. There's a command GGBOnInit that might solve this, but I don't know how to use this yet.

Pretty fun to make, and reasonably fun to play. I don't have students to play it with at the moment, so if you get a chance, let me know how it goes.

And - as always - if you have something you'd like to see made, drop me a line!