Introduction
One of the goals of the Urban Forestry program is to involve students in scientific research-type activities. Nearly all research is based upon data collection and analysis. Since all schools do not have access to beautiful natural areas, we would like to concentrate on the school site. As more and more schools participate in this study, we want to develop a network by which teachers from around the area can communicate and share ideas.

For this activity, we want participating schools to develop a data base which can be upgraded each year. To do this, you need to know the height and circumference of every tree on the your school site, and then chart the growth of those trees over the years.

Questions

1. How do we estimate the height of a tree?
2. How do we measure the circumference of trees?

Materials
Metric tape measures

Procedures

1. As part of Lab #1 , you may have started to develop a map of the trees on your school site. If you did not, you will need to have some way to keep a record of all existing trees and any new ones you plant.
2. Designate groups of students to gather data on the height and circumference of every tree on your site and record this information.
3. There are several methods by which your students can estimate or measure the heights of the trees. If your math curriculum includes Geometry, you may want to incorporate some of your math lessons here. If not, here is probably the simplest way:

1. Have students measure their own height (in cm).
2. Student A stands under a tree while student B stands a distance away. (about 20 paces)
3. Student B holds a pencil at arms length and covers part of the pencil so that the visible part is the same length as Students A's height.
4. Student B now moves the pencil up the tree and measures how many times taller the tree is than Student A.
5. Simply multiply this number times Student A's height and you have a good estimate of the tree's height. Example: Student A is 150 cm tall. Student B found that the tree is about four times taller than student A. So 150 cm x 4 = 600 cm. The tree is approximately 6 meters tall.

• Find the circumference of the tree by simply measuring. Tree circumference is usually measured at about chest height. To insure accurate measurements from year to year, you may wish to make a mark with paint in the bark to designate the exact place where the measurement is made.

Results
Please record your data on the forms provided.

Discussion Questions

1. What is the value of a "longitudinal" study?
2. Why is it necessary to study a tree for such a long time?