Exploding Dots
Exploding dots (suggested for 10 years old or above-this can get into some very high level math) The very basic explanation would be that it explores base 10, base 2, etc….in a very interesting way. I think this would be incredibly engaging for students of all ages.
Here is a quick link to a basic explanation - The 1← 2 Machine
Pre-exploding dots activities- for K-3 explores place value and arithmetic operations