Christmas tree Mystery Picture: Adding & subtracting to 30

A green Christmas tree with a yellow star on top, red ornaments and a brown trunk. The layered branches grow wider row by row, so children can watch the tree take shape as they color.

Children add and subtract with numbers up to 30 and cross ten along the way: 17 + 6, 26 − 8, 19 + 5, 30 − 12. Since every answer has to match a row on the grid, results never go past the height of the picture, and the bigger numbers appear mostly as the starting number in a subtraction, such as 27 − 9 or 24 − 7. That makes this topic particularly strong on subtracting across a ten from the twenties, which many children find harder than adding.