Addition and subtraction flashcards come with 9 different levels of cards that are color coded. Every time you introduce a new family, you get a new custom set of cards that focuses on that family, but also reviews previous facts. Not all twins are included, so if you have 3 + 4 you may not have 4 + 3. (Trying not to have overwhelming amounts of redundant cards, or cards that are too easy. For example, 9 + 1 is not in the up to 10's set.
Answers are also included, and the back of the card also states the level of the card.
1st level is teal and covers facts up to the fives. (18 cards)
Up to 6's, 7's, 8's, levels also have 18 cards
Up to 9's, 10's, 11's, 12's, 20's each have 27 cards
Also includes 3 self checking gameboards.