" As you can see from the following “top-down, bottom-up” illustration, learning takes place in two ways. There is a bottom-up chunking process where practice and repetition can help you both build and strengthen each chunk, so you can easily gain access to it when needed. And there is a top-down “big picture” process that allows you to see where what you are learning fits in. Both processes are vital in gaining mastery over the material. "

― Barbara Oakley , A Mind for Numbers: How to Excel at Math and Science (Even If You Flunked Algebra)