leaverou, 
I wanted to explain fractions to Zoe visually, but all relevant apps targeted older kids and were too complicated for my needs.
Took 15 mins to scratch my itch and prototype this in @CodePen: https://codepen.io/leaverou/pen/yLZdVMZ
Memorable URL / more robust layout version here: https://zoelearns.com/fractions/
The web devs among you may like how this the visualization is entirely drawn in #CSS — JS is only used to set two CSS variables :)
Video of the UI showing different fractions and a pie visualization
