There are inventions and inventions. Clearly useful (like the peeler), to a limited extent
useful (like most) and pretty useless (like Elon Musk's anti-zombies flamethrower). In front of me is a wooden box labeled “CLASSROOMCUBES”. Inside is a set of colored wooden blocks, a few colored clips, two dice and a booklet.
My verdict after over forty years of teaching: Absolutely useful! On it
I had been waiting all this time!