Pencil Method or Proportional Method
Measuring Heights  
       Have a friend whose height you know stand beside a tree, or tie a ribbon around the tree at your own height. Step back and hold a pencil or a stick at arm's length in front of you. With one eye closed, sight over the stick so that the top of it appears to touch the ribbon or your friend's head. Place your thumbnail on the stick where it seems to touch the base of the tree. Now move the stick up to see how many times this measurement goes into the height of the tree. Multiply that number by the height of your friend or the ribbon, and you will know the height of the tree. You can also use this method to measure buildings, waterfalls, and walls.