Acorn Mystery Picture: Adding & subtracting to 30

An acorn with a textured brown cap, a short stem and a smooth orange nut ending in a little point. The cap shows up first, so children can guess the picture before they finish.

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.