INRS State Scientific Surveys
GRADE LEVEL: K-3
SUBJECTS: Science, Math, Art
SKILLS: observing, critical thinking
OBJECTIVE: Students will learn that although we use trees for many things in our
daily lives, if we plan carefully, we will never run out of trees.
BACKGROUND:
Some of the natural resources that we use cannot be replaced. We
burn gasoline in our cars. Gasoline comes from oil that took millions of years to
make deep within the earth. Coal is often used to make the electricity that lights
our homes. Coal, too, took millions of years to make. Trees are called a renewable
resource because they can be replaced. But that does not mean we can waste trees.
It takes a long time to replace a tree. Before any tree is cut, there should be a
plan to replace it. For every tree that is cut, there should be a tree or trees
planted to replace it.
Christmas Tree Farm. Christmas trees are a good example of how trees can be replaced. No one wants to run out of Christmas trees, so they are grown on carefully managed farms . . . just like vegetables. Christmas trees are harvested when they are the right size, which takes from five to seven years. When trees are cut, new trees are planted so that every year there is a fresh crop of Christmas trees ready.
Paper Makers Are Big Tree Planters. The trees used to make paper are usually pine trees (softwoods), just like Christmas trees, only much bigger. Millions of acres are devoted to growing trees to make paper. When trees are cut, lots of trees are planted. This must be very carefully planned because it takes from 30 to 80 years to grow a tree big enough to make paper.
The Harder They Are, the Slower They Grow. Some trees can take a very long time to grow - a hundred years or more. These are the hardwood trees that we use to make furniture, floors, bowling alleys and baseball bats. The things that we make from these trees - which include oak, maple and hickory trees - can last a very long time. So with careful planning we can also replace hardwood trees as we use them.
Trees For Your Tomorrow. Remember, we don't just plant new trees so we can make
things from them. Someday your students will have children. And those children
will enjoy sitting under a cool oak tree on a hot summer day. They'll swim in lakes
and streams that are clear because tree roots hold the soil in place. And they'll
enjoy the wonderful, colorful spectacle of a trip through the country on a sunny
autumn day.
PROJECTS AND ACTIVITIES:
Have students, with their parents' help, identify the
oldest product in their homes made from wood. Students should draw a picture of the
product and bring it to class for a show and tell session where students describe
the product, its age and any interesting stories associated with it.
Are the desks in the classroom or the teacher's desk made from wood? If so, how old are they? If you can find out, help the class determine how old the students are who first used the desks. Discuss why wood might be a good material for desks.
Bring a cross
section of a small log to class and count the rings to determine its age. Measure
the circumference of the log with string and record it. Take the class on a short
tree hike, around the perimeter of the school or in a neighborhood and have the
students guess the ages of the trees they see by comparing them to the circumference
of the log. Measure the circumference of the largest tree you find with string.
Back in the class try to determine its approximate age in comparison to the log.
Plan a simple Christmas tree farm on the chalkboard. Draw a small Christmas tree that has just been planted and explain that in one year it will grow. Draw a larger tree to represent the second year of growth. The little tree now represents a new tree that you will plant. Add a third larger tree for the third year of growth. And so on, until you have five trees on the board. The biggest one is ready for Christmas. Now ask the class to discuss how the farm can be managed in the future so that every year there will be one perfect Christmas tree. Ask the students to draw a picture of their own Christmas tree farm.
EVALUATION:
Some products made from trees we use up quickly, paper for instance.
Other products last a long time. Some trees grow faster than others. Have the
class discuss, based on this information, what type of products we might want to
recycle and why.
EXTENSIONS:
Take the class on a field trip to a Christmas tree or certified tree
farm. Have the owner or manager explain the plan they use to plant and harvest
trees. If there is no Christmas tree farm nearby, visit a nursery where the growth
rate of trees can be demonstrated.
VOCABULARY:
renewable resource, mulch, compost, natural resource
Next lesson - People Who Work in the Woods