Pair, vintage Dolch popper numbers Arithmetic Learning Series, flashcards, c1958

2 boxes of arithmetic flash cards, subtraction and addition. Each box contain instruction on how to use the Arithmetic Learning Series developed by E.W. Dolch, Ph.D. The addition box contains 6 levels--16 flashcards per levels 1-2,4-6, and level 3 contains 20 cards. The subtraction box contains 6 levels-- 16 flashcards per levels 2, 4-6. levels 1, 3 contain 18 flashcards.