Calculate the height of a tree using only its shadow

How to do it

Find a big tree on a sunny day. Bring a measuring tape and a yardstick. Stand the yardstick straight up in the ground. Measure its shadow — let's say 20 inches. Now measure the tree's shadow — let's say 360 inches (30 feet). The math: (yardstick height / yardstick shadow) = (tree height / tree shadow). So tree height = (36 inches × 360 inches) / 20 inches = 648 inches = 54 feet. They write it out. Compare to another tree. They can measure anything now — the house, a telephone pole. They walk through the neighborhood pointing at things and saying 'that's about 30 feet.'

What you'll need

• Tape measure

  Free

• Yardstick

  Amazon

• Calculator (or phone calc)

  Free