Posted: Mon, 09/28/2020 - 11:18 am EDT
I just had a lot of fun reviewing binary numbers (and base-2 place value) with students using this Binary Circles "magic trick" today. I have students pick a number from 0-31, then I ask whether their number is in each of the 5 circles. Then utter some nonsense magic phrase and exclaim their number. It's a great attention-getter and helps to check their understanding of binary numbers. By the end, they're all excited to share this with friends and family too, spreading the message that CS is for all!
I was introduced to this at a CSPd, but apparently it's good background for CSA too: https://apcentral.collegeboard.org/series/strategies-for-teaching-ap-computer-science/binary-circles
I perform the trick on Zoom with students, but this could work well in-person too. Then, students could each take home their own copy of the circles to try.
Here's another resource explaining the trick: http://www.mathmaniacs.org/lessons/01-binary/Magic_Trick/