Turtle Mystery Picture: To 20, crossing ten

A turtle seen from the side, with a patterned green shell, a little head and stubby legs. The rounded shell appears first, and the head with its eye gives the picture away at the end.

All addition and subtraction facts up to 20 are mixed, including the ones that bridge ten. A child meets 9 + 4, 7 + 6 and 8 + 8 alongside 15 − 7, 12 − 9 and 11 − 3, plus easier problems that stay within one ten. Fluency here usually comes from make-ten strategies (9 + 4 = 9 + 1 + 3) or from doubles and near doubles (7 + 8 is one more than 7 + 7). Having both kinds on one page trains children to spot which strategy each problem calls for.