Understanding Automatic Differentiation in 30 lines of Python
I really enjoy small elegant code demonstrations like this that really allow you to get your hands dirty to try to understand a concept. Another example is Sasha Rush's gpu puzzles, tensor puzzles
-<a href="https://github.com/srush/GPU-Puzzles">https://github.com/srush/GPU-Puzzles</a>
-<a href="https://github.com/srush/Tensor-Puzzles">https://github.com/srush/Tensor-Puzzles</a>