Playing with this mechanical calculator teaches anyone arithmetic thanks to the magic of geometry. This little tree frog can multiply, divide, add and subtract as it jumps up and down on a triangle of numbers. This is an invaluable tool to teach, visually, the relationship between addition and subtraction, multiplication and division — and it’s way more fun for memorizing numbers than flash cards!
Download the template to make this clever frog with card stock and a few crafting supplies. You will need these mini metal fasteners or these tiny hollow eyelets with an eyelet setter for all the joints. Using a 1/16 Inch circle hand punch is recommended, rather than attempting to poke a hole in the correct spot. Precision matters!
See the mechanical calculator in action below!
View this video on YouTube. The frog is inspired by an old design by William Robertson, who, in 1916, designed a tin toy he named the “Educated Monkey.”