Measuring the Height of a Tree 

Information About Tree Height

Materials you will need:
   plastic straw, thread, tape, *protractor,
   measuring string (from the first activity), metal washer,
marking pen,
one stick (any length), paper, pencil or pen.

* The protractor should have a hole midway through
   the straight side.
   If no hole exists,  have one drilled,
or use tape to hold
   the thread on when you get to step #2.

Procedure to follow:

Part A - Build your Tree Measuring Tool

Follow these steps:
1. Use the marker to darken the line on the protractor

   that shows where 45 degrees is.

2. Cut a piece of thread about 12 inches long. Tie one end
    to the washer. Tie the other end to the protractor,
    through the hole in the center of the straight side.

3. Tape the straw along the straight edge, making sure that
    the straw follows the edge perfectly. Also make sure
    that the straw is straight. If it isn't, remove it and
    tape it again.

4. Practice looking through the straw. You should be able
    to see right through the straw.


Part B - Measuring the tree with your new tool

Follow these steps:
1. Pick a tree to measure.

2. Walk toward the tree until you must lift your head
    about half way up to see the top of the tree.
3. Hold protractor so that the side with the straw
    is on top.  Look through the straw until you see
    the top of the tree

    the thread.  Is the thread hanging straight down
    and passing across the darkened 45 degree line?
    If it is, go to step 5.  If it is not, do the following:
 If the
thread is hanging in front of the 45 degree line,
towards the tree.
    If the thread is hanging behind the
45 degree line,
    walk backwards away from the tree.

    Stop every few steps and look at the thread.
    When you can see the top of the tree through the
     straw AND the
thread passes straight across
     the 45 degree mark, STOP WALKING.

     Your situation will look like the picture below:

5. Bang a stick into the ground where you are standing.
    Measure the distance from you to the tree.
    Use your measuring string or use measured steps.

The distance to the tree (a) + your height (b)
             = the height of the tree.

Collect this data:
Measure the height of the 10 tallest trees in
your biotic community.
Be sure to give the species name of each tree
that you measure.

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