CECsci.159


TITLE:    Bark Casts

AUTHOR:   Darrell Spendlove,  Lewiston Elementary School,
          Lewiston, Utah

GRADE LEVEL:   Appropriate for grades 2-4

OVERVIEW:
When students look at a tree they often see only the leaves.
This activity will give them the opportunity to make careful
observations of the bark as well as learn to use bark to
classify and identify trees.

OBJECTIVE(s):
1.   Make a plaster cast of tree bark.
2.   Use plaster casts of tree bark to make a simple
     classification system.
3.   Use plaster casts of tree bark to identify
     individual trees.

MATERIALS:
Modeling clay, plaster-of-paris, pieces of poster board,
pins, an area with a variety of trees.

ACTIVITIES AND PROCEDURES:
     (Note, this activity can be done by individual
     students, or as groups of two, three, or four.)

1.   Cast Making;  Prepare by flattening out a stick of
     modeling clay so that it forms a rectangle about half
     and inch thick.  Press the flattened clay hard into the
     bark of a tree.
     (Make  sure that students push on the back of the clay
     as hard as they can.)  Carefully peal the clay off the
     bark and roll the sides into a long U shape.  Use
     pieces of poster board pinned into the clay to close
     off the ends to form a bowl.  Mix plaster-of-paris and
     pour into the bowl.
     Let it set.  When hard remove clay.
2.   Have students group the casts according to similarities
     and explain why they grouped them the way they did.
3.   Have the students or groups exchange casts and see if
     they can locate the tree that the cast was made from.

TYING IT ALL TOGETHER:
Discuss with students the importance of making careful
observations.  You may want to have the students paint the
casts to make them look like the bark.  Be sure that they
try to make there colors match the bark and not just paint
it brown.