I love the prework section: https://developers.google.com/machine-learning/crash-course/... It's a very good mix of topic and skills that I think everyone should learn, even if not directly planning to do ML or DL. If y'all are looking for a compact (and inexpensive) textbook on linear algebra that comes with all prerequisites you can check out: https://gum.co/noBSLA (disclaimer: I wrotes it)