Six family pictures, each with an empty box in the corner for the answer. A dad and his son, a family of four, a mom walking with her daughter and a baby, and then two big three-generation families with grandma and grandpa standing at the back. Count everyone in the picture and write the number.
The counts run from two to seven and are not in order, so a child cannot guess the next answer from the last one. The larger families are the real work: the children stand in front of the grown-ups and partly hide them, so a child has to touch each person once and keep track of who they have already counted instead of sweeping along a tidy row.