Spider Mystery Picture: To 20, crossing ten

A friendly purple spider with big eyes and a smile, hanging from a thin thread. Its eight black legs appear one by one, which makes it a fun, not-at-all-scary picture for Halloween.

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.