Testing yourself beats rereading, even though it feels worse.
In 2006 Roediger and Karpicke had students either read a passage four times, or read it once and write it from memory three times. After five minutes the rereaders were ahead. After a week the retrieval group remembered 61 percent, the rereaders only 40 percent. Recalling is learning.
Useful: Close the book and write down what you still remember.
Source: doi.org