The method of Active Recall is a very simple one. You can read about this in The Science Behind Best at Biology section. You test your brain by asking questions, instead of just reading content.
For example, lets pick Human Nutrition.
As you can see here, all the info is controlled by toggles.
A question will be asked, you must answer the question, by either saying it in your head, writing it down, or by drawing the diagram if asked.
Lets look at the question “Draw a diagram of the human digestive system”
You would draw a diagram of the human digestive system as best as you can without using your notes.
After you finish drawing your diagram (or answering the question, simply click on the toggle to reveal the answer
If you were correct, move onto the next question.
If you were incorrect, draw out the diagram or answer the question again, until you can get it right without looking at the answer.
To close the toggle, just click on it again.
Tip : When learning content for the first time, repeat it 3 times before moving on to the next question. This again is scientifically proven to help retain info into the long term memory
Do not just mindlessly skip through the toggles, take it slow, one toggle at a time. You will reap the rewards.