I am taking an online course from wismon.nl (it is a Dutch course). They use the regular high-school textbooks that are used in The Netherlands; "Getal & Ruimte".

This might not be of much use to you if you're not a Dutch speaker, but one thing that seems to work very well for me is just going through the exercises in the textbook! On top of that, there are quite a lot of amazing explanation videos on YouTube if a topic is hard to understand.