Biology asks you to hold a great deal in your head and to understand how several moving systems fit together. Those need different treatment: the systems are worth interacting with until the shape of them is obvious, and the facts are worth scheduling so they come back before you lose them. A plan here does both rather than treating everything as reading.
The circulatory loop, running whether you watch it or not. Click any stage.
Blue is blood that has given up its oxygen, red is blood that has just collected some. Click any stage to read what happens there.
You describe the goal in your own words and it asks questions back until the plan is one you would actually follow. These are the shapes that goal usually takes.
Not a fixed syllabus — the plan is built around your goal and cuts what does not serve it. These are the topics it draws from, and whatever you get wrong comes back until it stops coming back.
The mechanics are the same whatever the subject — a slider is a slider whether it is moving a coefficient or a rate of return. What changes is what it is a slider for.
Or see how it works and what it costs.