I love the EDC's SolveMe Mobiles (https://solveme.edc.org/Mobiles.html) and have made similar applets (https://www.geogebra.org/m/mtfc7xvc) and even some imbalance puzzles (https://www.geogebra.org/m/h2hkQWj2).[br][br]But I loved this suggestion from Professor Smudge on Twitter, and had to make one that is more explicitly algebraic. https://twitter.com/ProfSmudge/status/1332291517642403846?s=20