SymPlay

Is it an animated calculator?
An interactive algebra solver?
A codeless manim interface?

Idk what it is exactly but here it is. From the main menu you will see three modes.

The primary mode is the Timeline Editor. Here you can create a timeline of algebra/arithmetic expressions and animations transitioning between them. Just click New Timeline and type in your desired starting expression, then use any of the action buttons on the right side to create animations to modify it one step at a time. In the bottom left are buttons labeled Solve and Evaluate which will produce long sequences of actions automatically. Solve will isolate any chosen variable in an equation (unfortunately it limited to variables that appear exactly once in the equation) by moving things across the equals sign appropriately. Evaluate will perform arithmetic operations on number expressions one step at a time until it can't do any more, which I often combine with the substitute action. Results can be directly screen recorded within SymPlay or can be exported in a variety of formats.

The second mode is the Equation Game, where the player guesses the solution of a given equation, and the substitution and evaluation is automatically animated. One can choose the difficulty, number of points needed to win, and whether the equations are handcrafted or randomly generated. I have played this game with many of my students and it's a lot of fun! I think it would be a really great classroom warmup.

The third mode is the Piano Viewer, a live visualizer for piano intervals and chords. It automatically detects a midi device connected to your computer, and then presents what you are playing to you in real time in a few customizable ways. Above the keyboard it shows the half-step distances between the notes, and it also has places the 12 notes in a circle and shows the "shape" of any chord in that world too. I have found both of these to be really fruitful and illuminating ways of thinking about chords and harmonies. I hope this will be useful to all musicians, enthusiasts, teachers, and students!

This whole thing is actively in development and will surely have some bugs. The core technology is my custom computer algebra system that I made specifically for the purpose of animating each step, as I found that no existing computer algebra system was designed in a way to allow for this. This library can be found on my github. SymPlay sprung up around it as a codeless way to engage with it and I just kinda kept going. Thank you for your interest and I hope you enjoy.