Mountains Mystery Picture: To 20, crossing ten

Two grey mountains with snowy peaks, green hills in front and a yellow sun in the sky. The peaks appear first and the slopes grow wider row by row, so the landscape takes shape quickly.

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.