I have found that my kids need a lot of repetition and review to retain information, so I came up with a handy review system for history and science, our only two subjects that don’t easily offer daily review.
I write down key facts and vocabulary, usually in Q&A form, on 3X5 index cards. I usually write the question or vocabulary word on the front and the answer or definition on the back.
Then, I punch a hole in the corner of the cards and put them on a ring similar to a key ring except that it opens so that the cards can easily be placed on the ring. The rings are inexpensive and easily found at most mass retailers (i.e. Walmart and Target) or office supply stores. I then put the ring around one of the three rings in the binder for each subject, so that the cards are easily accessible and always with the right book.
This makes it easy to review a little each day, as well as at the end of units and randomly throughout the year so that important facts are not easily forgotten.