The theremin is a peculiar musical instrument. Here is a theremin-like software I created together with my two daughters. The instrument is simple, just draw your mouse over the pink area, the higher you go on the screen the louder the sound, and the more to the right, the higher the frequency. Actually it should work best on a touch screen, but I haven’t tried that myself. There a five buttons that create five different sounds. Simple as that.
Tal-i-rad is a ”five in a row” math game that you play against another person. I made it together with one of my daughters to make it more fun to practice math. The game starts of quite simple, but as you keep answering correctly, the time you have for each question gets reduced. In this way, the game gets rather even, even if you compete against someone who solves each questions much faster.