Teach your child to measure the height of a tree or building by measuring its shadow in inches.
Measure the shadow of a 12 inch ruler (in inches). Then calculate the tree's height as follows: divide 12" (height of the ruler) by the length of its shadow. Multiply that result by the length of the tree's shadow. Example: if the ruler's shadow is 6 inches and the tree's shadow is 120 inches, the tree is 240 inches tall. 12 / 6 * 120 = 240 inches.