Science and Children >  > Green Mansions > For the Classroom 
falling leaf graphic

For the Classroom

Stop the Flow!
This activity simulates protected versus unprotected streamsides. Students compare and contrast the situations and analyze the effects on aquatic systems.
Background: A key aspect of watershed restoration and aquatic habitat improvement is reducing sediment flow into streams. Logging on slopes and road construction also contribute to erosion. The best way to keep landslides and surface sediment from reaching streams is to leave a buffer zone of vegetation in place on either side of the stream.
Question: What is the difference between the amount of sediment found in a stream with a buffer zone as opposed to a stream with no buffer zone?
Materials: cookie sheet, aluminum foil, lightweight cotton cloth, potting soil or dirt, sod, a water bottle fitted with a sprinkler head or sprayer.
1. Using crumpled aluminum foil, make a hilly landform shape to represent deforested slopes. The "hill" should have a crest but should not be too steep on the sides. Place it lengthwise in the center of the cookie sheet; the aluminum foil should reach the short ends of the cookie sheet. Loosely drape the cloth over the hill. Along one long edge, tuck the edges of the cloth under the foil. Along the other long edge, place the cloth edge under a strip of sod that is about 5 cm wide. Scatter soil over both slopes.
2. Explain to students that the model simulates deforested slopes with streams on either side. The side with the sod simulates a stream with a buffer zone. Ask students to predict and observe which stream will have the most sedimentation.

Graphic showing a hilly landform representing deforested slopes.

Shelly Fischman

3. Using the bottle of water fitted with either a sprinkler head or sprayer, douse the hill with water, getting even amounts of water on both sides. The soil should "erode." Students should notice that the buffer zone stops the sediment from going into the stream, while the unbuffered side unloads abundant sediment into the stream.
4. Using information from the article, discuss with students the effects of sedimentation on aquatic species and water quality.

What Is Wood?
Students list products made from wood, add to the list through research, and analyze their list to differentiate two categories of wood products.

Background: Wood products are essential to our lifestyle and survival. Many products contain components derived from wood that may not be obvious. Wood is a renewable resource and much of our wood today comes from tree farms. These are not really forests, for they lack the ecosystem relationships of a natural environment; rather they are monoculture crops (single species). Forests also provide a great deal of our nation's wood supply. On average, every person in the United States consumes the equivalent of one tree a year in wood products, including 306 kg of paper.
Question: What wood products do we use in our everyday lives and how can we make wiser use of this natural resource?
1. Ask students to list items in their daily lives that are made or derived from wood. You may want to share some ideas from the next column.
2.Duringa class discussion, make one list on the board from the students' lists. Leave the list where it is visible and give students the opportunity to research other products made from wood. Some of the Web sites listed in the Resources section of this article provide such information.
3. Continue the discussion, adding new products to the class list based on students' research. Now have students consider which wood products are recyclable and which could be used more efficiently.

From a tree:
baby food
rayon fabric
floor tiles
football helmets
computer casings
cleaning compounds
rubber tires
photographic film
home insulation
railroad ties
animal feed
paper and cardboard
tea bags
sausage casings
shoe polish
oil filters
fish food
Christmas trees
diving boards
golf balls
paint remover
cascara bark

Floral industry materials:
transplant shrubbery

Three Volcanoes
This demonstration illustrates the three types of volcanoes. Students predict the types that will form from the demonstration and compare the results with illustrations. (This demonstration is adapted from Volcanoes! Teaching Guide, U.S. Geological Survey.)

Background: There are three types of volcanoes distinguished by the kind of material that erupts from them and how it builds up over time. Shield volcanoes are low and gently-sloping; they eject a fluid magma that flows slowly. Stratovolcanoes (sometimes called composite volcanoes), such as Mount St. Helens, are shaped by built-up layers of thick lava alternating with tephra, the airborne fragments of magma that range in size from fine ash to giant boulders. Stratovolcanoes are the classic cone-shaped volcanoes. Cinder cones are small volcanoes containing lava that, when airborne, forms into cinders and then falls back to Earth in a cone shape around the volcano's lava vent.
Question: How do different types of volcanoes form?
Materials: three pie plates; three one-cup measuring cups; two cups cat litter, sand, or sugar (simulating tephra); two cups chilled molasses or thick mixture of plaster of Paris (simulating lava); a protractor; a metric ruler.
1. Explain to students the different types of volcanoes and draw their shapes on the board. Use the illustrations labeled master sheets 1.1, 1.2, and 1.3, found at as a guide. Tell students which materials represent tephra and lava. As you prepare to make each of the three models, students should predict which type of volcanoes the materials will form.
2. In one pie plate, from a height of about 50 cm, slowly pour one cup of the tephra material. In another pie plate, from a height of about 20 cm, slowly pour one cup of lava material. In the third pie plate, alternate layers of tephra and lava, again from a height of about 20 cm. Students should observe the shapes as the tephra and lava are poured.
3. Let students compare the shapes of the models with the illustrations and discuss how the materials ejected from a volcano determine the shape of the volcano. Use a protractor to measure the slope angles of the three types of volcanoes. Let students look at photographs and Web sites showing the volcanoes in the Northwest and determine which kind of volcanoes are found there (strato-volcanoes). The following Web sites include images of volcanoes in the Pacific Northwest: and

Artist's depiction of the three layers of the temperate evergreen forest
The three layers of the temperate evergreen forest: the canopy, the understory, and the forest floor.

Shelly Fischman

A Crowd of Plants
Changing the space allocated to plants simulates conditions in the rain forest. Students observe, record, compare, and contrast the changes and apply the knowledge from this experiment to the rain forest situation.
Background: Plants need air, water, sunlight, soil, and room to grow. Plants that grow too closely together compete with each other for the other essentials of plant life and are often stunted and weak, making them especially prone to disease, fire, and windfall. In the rain forest, few plants can successfully germinate and grow under the old-growth's dense canopy, which blocks out sunlight. New plants can get a vigorous start when an old tree dies or when disease, fire, or windfall create an opening in the canopy through which sunlight penetrates.
Question: How does shade affect new plant growth in the temperate rain forest?
Materials: about two dozen seeds (pea, bean, or tomato), a large pot with drainage, soil, scissors.
1. Plant three or four seeds in the corners of the pot, allowing about 15cm between them. Water the seeds and place the pot where it will not receive direct sunlight for about ten days. After ten days, move the pot to a place where it will receive direct sunlight. Water the plants and have students record the progress of plant growth.

Old-growth forests contain trees that are more than 200 years old. The Northern spotted owl, a threatened species, depends on these forests for its habitat.Photo of an old growth forest


2. When the plants are about 15 cm tall and leafy (about three weeks) plant one to two dozen additional seeds in between the seedlings, being careful not to disturb the existing plants. Students should observe and record the progress of these new plants (they will be stunted and will not grow well).
3. After about three more weeks, remove one of the first plants and all but two or three of the stunted seedlings near it. (Remove them by cutting them off at the ground level, so the root systems of other plants will not be disturbed.) Students can record the growth of the plants in the thinned area and contrast these measurements with the other stunted seedlings, which should begin to thrive.
4. In a class discussion, draw the parallel of the potted plants with the rain forest plants and how shade affects growth there.

Back to the Green Mansions homepage

falling leaf graphic