I wrote this for my five year old son whom I first showed some calculation exercises on an MSX emulator. He seemed to like it but the interface was a bit more cumbersome than it would have been on real hardware, so I decided I would write something myself.
There is of course ample software for this specific purpose available, for tablets, phones or even actual computers, all really colourful and probably very pedagogic. However, even when they don't explicitely ask for permission for the devices' front camera and mic, you still need an account and you'd be sure there is a company (or more likely, dozens) slowly building a profile on your kids.
So, this just works in Java (which you most likely already have on your computer). It runs on your computer's desktop, and no internet connection is needed to run it. You also need no account nor anything else. You just tell it what kind of exercises you want and there you go.
TODO: - Input fields and buttons always get focus - Internationalize (All texts are in Dutch) - More assignments type - Involve more dino's - Sound