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Measuring the height of a tree

You need to know

• how to measure an angle in degrees

You will need

Steps

1. Fold the short edge of your card onto the long edge in a triangular point.
2. Cut away the rectangle on the end so you're left with a square.
3. There is already a diagonal fold on the square. Fold it back into a triangle and tape the edges to keep it closed.
4. The two short edges of this triangle are the same length. Use the protractor to measure the internal angles of the triangle. One should be 90° and the other two should both be 45°.

Keep safe!

Don't try to measure a tree near a road.

Make sure the string is not in anyone else's way.

5. Tie the end of a ball of wool or string around the trunk of a tree at the height of your eye.

   Make sure it is tight so the knot in the string is very close to the tree.

6. Reel out the string until you are about as far away from the tree as the tree is tall.

7. Hold the string to your eye, and hold the card triangle to the top of the string so it forms a 45° angle. Move your eye and the triangle along the string until there is a straight line from your eye to the top of the tree along the hypotenuse (long edge) of the triangle.

   

Keep safe!

Don't look directly at the sun.

8. Measure the length of the string from your eye to the tree and write it down.

Hint

You could write it on your triangle if you don't have any other paper.

9. Measure the height from your eye to the ground (or from the string round the tree to the base of the tree, which should be the same).

Questions

1. How tall is the tree?

Explore further (optional)

Find some other objects to measure in this way.