First you need to make the measuring device. You will need...

• a piece of stiff cardboard
• a pencil and a ruler
• a roll of sellotape
• a piece of string 23cm long
• a metal nut
• a pair of scissors
• a drinking straw

First draw a triangle on your cardboard. Two of the sides should be 15cm in length. Cut out your triangle.

Tape the drinking straw to the long side of the triangle. Now on one of the 15cm long sides draw a line 2.5cm from the edge. At the drinking straw end of this line measure 2.5cm down and poke a hole through the cardboard.

Thread one end of the string through this hole and tie it to the cardboard. To the other end of the piece of string tie the metal nut.

Now you are ready to measure a tree.

Look at the top of the tree through the drinking straw. Move your measuring device until the string is laying exactly on top of the line you drew on the triangle and the nut is hanging towards the ground. Someone else will have to check the line/string while you look through the straw.

The closer you are to the ground the more accurate your measure will be.

Once the string lies upon the line and you have the top of the tree in view (you will have to move several times before this happens) then that is the spot where you measure from.

Measure the distance on the ground from there to the base of the tree. That distance is exactly equal to the height of the tree!

Well Done! Now you can impress your friends and family! Why not try finding the tallest tree in the neighbourhood and have a contest with your friends to find a taller tree!