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A Little Bit More

Trees are so much a part of our lives that we take them for granted. Very few areas in the U.S. or Canada are without trees, and treeless areas usually have few people – the two seem to go together. Wood and wood products are such an integral part of our daily lives that it’s hard to imagine life without them.

Throughout history, trees have been used to provide fuel, food, shelter, fiber, medicine, weapons, tools, vehicles, containers, building materials, and art objects. Despite the widespread use of wood substitutes today – plastic products, for one – wood and wood products are still in heavy demand all over the world.

Since the “dollar” is often the deciding factor in whether something is implemented, researchers have looked at energy consumption by air-conditioners as it relates to trees. Although it is well known that trees provide cooling shade with their leaves, as well as cool the air through transpiration (evaporation of water from the leaves), providing a research-based dollar figure on these benefits was an important component in convincing people of this fact. One study released in August of 2001 found that tree cover in the metro Atlanta area saved residents approximately $2.8 million annually in reduced energy costs. In 1999, a 3.2 million acre area around Houston was found to benefit by $26 million annually as a result of the cooling effects of its tree cover. Similar trends have been found throughout the country.

Activities

Science & Math – How Many?

This is a simple enough activity yet one that should help younger students integrate how important trees are in their daily lives.

Have someone list on paper or the blackboard the uses for wood as they’re noted by the students within your classroom or home.

Look around the room and look for as many items as you can identify that are made from wood or have some wood incorporated into their production. I’ll give you the first one.

1. Pencils – the wooden part that surrounds the carbon
2. ...

I hope you didn’t forget to include paper too!

Science - How Many?

For older students, you may want to try this estimation activity. I think you’ll find that most students are not very comfortable in their estimation skills so they should find this an enjoyable, interesting, and worthwhile exercise.

This is a good fall activity when the leaves are ready to fall and you can remove them without harming the tree.

1. Decide on one of the trees in your area that you’d like to focus on. It will be best to select a tree that is not too large or too small (you need to be able to reach a single branch for leaf removal)
2. Once you’ve selected your tree, have the students walk to the tree and ask each one to estimate how many leaves they “think” are growing on the entire tree. Be sure that each student knows to consider that the leaves are growing all around the tree when making their estimate.
3. Now tell the students that you’re going to determine how many leaves are on the tree using an “estimation technique” that should provide a reasonably accurate number - should give us a “ballpark” figure..
4. Select a lower branch that you can reach and have your students estimate what portion of the tree’s leaves it constitutes (ie. The selected branch may be holding about 1/40 of the entire tree’s leaves).
5. Now have the students cut the petioles (connection between leaf and branch) of all of the leaves on your selected branch, assemble the leaves, and count them.
6. Once you know the exact number of leaves that were on your sample branch, you can multiply your sampling of leaves times the fraction of the tree it constituted (ie. 206 leaves in our sample count X 40 = 8,240 leaves on entire tree).

No, this is NOT the exact number of leaves on our tree but we’re in the right “ballpark” with this number. Often we need to have an approximation of leaves on a tree, not an exact number and this technique does just that. This exercise provides students with some kind of reasonable way to determine the number of leaves. It will be interesting now to review what the students first put on their papers when asked about how many leaves were on the tree. This ballpark estimate gives everyone a frame of reference to go on.

Key Concepts

Environmental Issues

Questions

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