Once the leaves are off the trees in the fall, it is amazing how much easier it is to see some things. Trees are still beautiful as their trunks and limbs come into view. It's a great time to figure out how tall trees are. Here are several ways to measure the height of tall objects. Use them to find the height of some trees near your home or school.
Stand a person whose height you know in front of the tree. Walk away from the tree until you are far enough from the tree to cover the person with your thumb or a pencil. Count the number of thumb heights from the bottom of the tree to the top. For example, if the person is 4 feet tall and the tree is 4 persons (thumbs) high, then the tree is 16 feet tall.
A second way is to walk far enough from the tree that the length of your thumb covers the whole tree.
Then turn your hand so that your thumb points from the bottom of the tree out along the ground. Notice where the end of your thumb seems to end on the ground. Measure from the base of the tree to the spot where the end of your thumb was. That is the height of the tree.
Another way is to compare shadows:
Measure the length of the tree's shadow. Measure the length of the shadow made by a person whose height you know. Express this as a ratio and solve it for the height of the tree. For example, the tree shadow is 20 feet long, the person is 4 feet tall and has a 5 foot shadow. Call the height of the tree h.
h is to 20 as 4 is to 5
h/20 = 4/5
5h = 4 x 20
5h = 80
5h/5 = 80/5
h = 16 feet
Can you figure out any other methods? Can you think of some other tall objects to measure?