Children will find the tallest tree to measure its height. Keep track of its current size. A tree's circumference, diameter, and height are the tree's best indicators; expect change. Circumference is a measurement of the distance around the trunk of the tree. Normal ratio is height of four and a half feet(breast height). Note that if a tree grows on a hillside or slope, its circumference is measured at four and a half feet above the ground on the uphill side. You must have consistently been in these measurements.

How to Measure Circumference (Visual Picture)

To take your reading, wrap the tape measure snugly around the tree trunk. (If the tape measure isn't flexible enough, wrap cord or twine around the tree.) Mark the spot by pinching it and measuring it with the tape. 

The diameter of a tree is the distance straight through the trunk, and it's calculated by first measuring the circumference and dividing that by pi(3.14). If the tree measures 22 inches, it's approximately seven inches in diameter. Scientists have discovered that, because it resembles the trunk of a tree, the empty tube from a roll of paper towels or bathroom tissue can help your child visualize the concepts of circumference and diameter as they relate to a tree. Lastly, the tricky part is the tree's height, particularly for tall trees. With some everyday objects and some basic geometry, you and your child can have fun measuring the height of your tree with a fair degree of accuracy.

Shadow Method

What you need

• A sunny day
• A yardstick
• A tape Measure

What to do (Visual Picture)

1. Place one end of the yardstick on the ground and hold it so that it stands straight up. Using the tape measure, find the length of the yardstick's shadow.
2. Compare the length of the yardstick to the length of its shadow. This same ratio will apply to the tree's height and shadow length.
3. Measure the length of the tree's shadow and apply the ratio to determine its approximate height. For example, if a three-foot yardstick casts a two-foot shadow, a tree casting a twelve-foot shadow would be eighteen feet tall.

Triangulation Method

What you need:

• A piece of paper or cardboard
• A level
• A tape measure

Square off a letter-sized sheet of paper or cardstock by folding the top edge so that it lines up perfectly with the left-hand edge. Crease the paper and remove the excess; this creates a right isosceles triangle with two sides of equal length. (Side Notes: The triangle size isn't essential, but the two equal sides separated by a right angle are.)

Start by standing in a spot about as far from the tree as the tree is tall, hold the triangle so that the two sides of equal length are vertical and horizontal.

Looking along the triangle's long edge(the hypotenuse), move forward or backward until you can see the top of the tree along its length. Using its level to fine-tune your instrument, your measurement will be inaccurate if the triangle is tipping up or down. Once the top of the tree is lined up, measure the distance from the observer to the base of the tree. Then add the distance from the ground to your eye level. The total will give you the height of the tree.