A Close Encounter of the Tree Kind

Charles T. Buzek               Spry School
                               2400 S. Marshall
                               Chicago IL 60153                    
                               (312) 354-1400

Objectives:
               
    These activities are designed for a 6-8th grade setting.
    Students will learn how to estimate the heighth of a tree.
    Students will learn that bark can be a distinguishing characteristic of
     trees.
    Students will learn how to make a bark print.
    Students will learn how to estimate the age of a tree.
    Students will learn the respiration rates of trees.
    Students will learn about turgor in the tree's internal transportation 
     system and how it is affected by the sun.

Materials Needed:

    A sheet of carbon paper
    A large piece of art or construction paper
    A ruler
    Plastic baggies
    A meter stick
    Sections of string at least six feet in length
    Masking tape

Strategy:

    This is an outdoor activity that will allow your students to gather 
    information in the same way that scientists do.
    Select teams of students (three or four in each group).

First activity-Tree measurement
    Each group to select a tree.  One member will position themself next to the 
    tree.  Another will take the ruler and step forward or backward until the 
    ruler exactly fills the heighth of the tree.  With this accomplished the 
    student with the ruler will move the top of the ruler from a vertical to a 
    horizontal position making sure that the base of the ruler still sights at 
    the base of the tree.  In this position the student will sight down the 
    other end of the ruler and identify some object in the same line as the 
    tree.  Once identified, a member of the team will go to that spot, then pace 
    out the distance from that point to the tree.  This is the heighth of the 
    tree reduced to a horizontal linear measurement. 

Second activity-Age estimation
    Scientists estimate that mature trees grow at a rate of an inch a year. 
    Students can select mature trees, measure them around with a tape measure or 
    string with a meter stick, and then compute the average age.  This activity 
    will allow your students to add another piece of information in their 
    description of a tree. 


Third activity-Bark rubbing
    Each species of tree has a distinctive bark.  Students will be able to use 
    this information to identify trees during the winter when there are no 
    leaves.  It is useful for students to see that while trees conform to a 
    general image they are in particular quite different.  Student teams will 
    tape large sheets to a tree and then, using the carbon paper, will rub over 
    the bark creating an image which reproduces the texture of the tree bark. 

Fourth activity-Water loss
    Each group to fasten a baggie on an individual leaf and leave it there for 
    an hour.  Placement of the leaf should involve experimentation some should 
    be in the shade, others in the sunlight.  After an hour the baggies should 
    be collected and the water collected should be poured into a graduated 
    cylinder. 

Follow-up activity
    Students will collect leaves and twigs from the tree.  With all of the 
    information collected the teams can now make a display providing all the 
    information that they have collected. 

Performance Assessment:

    Students will have successfully mastered the activities in this exercise
    if they can do the following:

    Describe the process used in measuring a tree.
    Describe the theory behind age estimation.
    Describe a theory for water loss difference in leaves on the shady side as 
     opposed to the sunny side.