We forget what we learn very quickly. A day after a lesson if we have done nothing with the information we learned then and didn't think about it again, read it again, etc. we will have lost 50%-80% of what we learned. Seven days later, we remember even less, and by day 30, we retain about 2%-3% of the original! After each lesson we need to revise and practise new material so that we can remember it and so do projects, tests and exams easily with the knowledge we already have.
We remember things much better if we go over them very soon after we first learnt them. On the same day we get the information, if we spend ten minutes reviewing, we will remember almost all we learnt. A week later, if we take 5 minutes to "reactivate" the same material, we can still retain almost 100%. By day 30, our brains will only need 2-4 minutes to give us the feedback, "Yup, I know that. Got it."
