Children of the River
Sample Discovery Activity: Go With the Flow
Many factors control the course and the life of a river. Some of them are
natural, such as rain and temperature. Others are the result of human interaction
or engineering, such as pollution and the construction of dams or locks.
For example, when natural barriers are removed from a river's banks, high
levels of phosphates and nitrates from fertilizers and animal wastes can
be carried by the watershed run-off into the river. This leads to a process
called eutrophication, or an increase in plant life in the aquatic environment.
More plant growth may result in slower running water and the stagnation
of the river, which in turn reduces the dissolved oxygen content of the
water, making it a less hospitable environment for the plant and animal
life in it.
The erosion of a river bank will be affected by the volume of water carried
along and the speed of water flow. People have contributed to the erosion
process by diverting the natural paths of rivers and streams. They have
also increased the rate of change by disturbing vegetation which grows along
the banks. Sometimes, human interaction works to slow the erosion process.
For example, planting along a river bank will make the soil less susceptible
to being carried away.
As you will recall in the video, Children of the River, the river on Walpole
Island was changed due to excessive pollution by nearby industrial discharge.
Some industries pollute not with chemical, but with thermal, discharges.
Higher temperatures decrease the ability of the water to hold oxygen and,
like the eutrophication process, will affect a river's ability to sustain
life. In this lesson, the students will learn more about how people can
affect the course of a river. They will demonstrate the process of erosion
by making a small river box and read about individuals who work every day
to harness the river for our benefit.
Objectives
The students will:
1. create a river in a small box to witness the erosion process.
2. describe how the process of erosion changes rivers and streams.
3. identify science careers.
Time Allotment
one 60-minute session
Materials
maps of local river
1.9 liter cardboard milk cartons
2 liter bottles
sand or soil
containers to catch water and sediment
a metric ruler
scissors
water
garden trowel
journals
pens or pencils
Advanced Preparation
Arrange the students into cooperative groups.
Procedure
Tap Prior Knowledge
1. Ask the students "What do you know about the shape of rivers? What
role does a river or stream play in changing its own course? What is erosion?"
Share with Neighbor
2. Have the students work in their groups to study old and current maps
of a local river, looking for changes in the its course or in the surrounding
environment.
Hands-on Activity
3. Distribute one milk carton, a 2-liter bottle, some sand or soil, a container
to catch water and sediment, a metric ruler, scissors, water, and a garden
trowel to each group.
4. Have the students set up a river box by cutting off one side of the cardboard
milk carton and placing it on its side. There should be a hole at one end,
where the milk used to be poured, for water drainage. Position the container
for water and sediment under this opening.
5. Put the soil in the container, filling it 1/2 full. Smooth the surface
with the garden trowel.
6. Prop up one end of the box. Run some water through the box. Experiment
with different levels of propping the box up for best results. Try not to
form a lake, but let the water run slowly enough to carry some sediments
along with it.
7. Keep pouring the water from the two liter bottle onto the soil with an
even flow. Watch the path cut and the depth of the riverbed. Stop pouring
and make measurements of the river's path. Measure from the outside of the
box at several points along the river, or use pencils stuck in the sand
for measuring points. Have the students record the measurements in their
journals.
8. Continue to pour water in the river box. Observe and discuss the process
of erosion with the students. Make measurements and record how much the
river path has changed.
9. Add more soil and then see what happens. Begin with an S-shaped stream
and experiment with the speed of water flow. What happens when some of the
sand is removed and the water is allowed to flow more directly?
Proposing Explanations and Solutions: Introduce the Scientific Concept
10. Encourage the students to reflect on the forces they are witnessing
by writing in their journals or by telling a partner. How have their views
changed, if they have changed, since before the activity?
11. The course of a river is formed by natural forces. The water flowing
along cuts the banks and carries sediments along to be deposited at its
mouth. What happened in the river box is what happens, on a larger and more
gradual scale, in nature. Rivers are formed and their courses are changed
when the bank erodes and is carried downstream. Construct other models or
drawings.
Connect to Other Everyday Examples
12. Erosion takes place as a result of forces like wind and glaciers. The
most effective tool of erosion is water. Streams of running water wear away
rock and move sediments downstream. The results of this erosion are evident
in our environment. The Mississippi River, for example, carries about 600
million tons of rock particles each year. This sediment is deposited at
the mouth of the river, in the Gulf of Mexico, creating the Mississippi
Delta which can be seen in aerial photographs. The Grand Canyon, also, was
formed after millions of years of water running through it. The erosion
process is a powerful component of the natural rock cycle.
13. Use examples of the recent flooding of the Mississippi River to illustrate
how the course of a river changes.
Home Activity/Parent Involvement
Following this activity, the students should be encouraged to share what
they have learned with their parents. They can respond to the following
questions by completing a journal entry:
1. How does the water move the sediment and the soil?
2. How does water shape riverbeds?
3. What was water carrying down the river or on the river?
4. Where did the sediment come from?
5. How did the water cut a riverbed?
6. What effect does human interaction or engineering have on a river?
Lesson Assessment
Collect the student's journals and read their answers to the questions assigned.
Their writings should demonstrate an understanding of the erosion process
and how rivers and streams are formed.
Books to Read
ABC's of Ecology, by Isaac Asimov, Walker Books
Ecology: The Circle of Life, by Harold R. Hungerford, Children's
Press
Elementary Science Study, Water Flow, by David R. Stronck, McGraw
Hill/ National Science Teachers Association, 1971
Guardians of Tomorrow: Pioneers in Ecology, by S. Carl Hirsch, Viking
Press, 1971
Tom Sawyer, by Mark Twain, Pendulum Press, 1973
Taking Action/Additional Activities
Return to Children of the River
Return to Chicago Science Explorers
Return to The Chicago Academy of Sciences