Third-grade students plant
native plants on school grounds
to test soil-retaining strategies.
By Martha Smith
D
riving to school one bright, beautiful day last
spring, I tried to figure out how to take my
plant lessons outdoors to wrap up what my
students had been learning inside. Throughout the spring term, the third graders had learned how
plants need air, light, nutrients, water, and soil to survive. They had also learned about several plant “tions”—
fertilization, germination, nutrition, respiration, and
circulation. I wondered how to translate what they had
learned into something practical and useful. How could
we take advantage of the nice weather and bucolic school
grounds to learn about plants?
With the goals of making what I had taught practical and
enjoyable for my students, plans for a soil conservation activity began to take shape. The learning objectives were for
students to: (1) Apply soil conservation methods to growing
plants and (2) Collect data and draw conclusions about the
effectiveness of their method of soil conservation.
44 Science and Children
Teacher Planning
First, I contacted a parent who oversaw the plantings on
the school property. The parents and students in each
grade are responsible for specific plots of ground at the
school, which they continue to tend year after year. As
it happened, the third grade had not yet been assigned
a garden plot. I was looking for an area students could
walk to, preferably on a slope and with partial shade. We
found a place meeting those prerequisites and assigned it
to the third grade. Using the parent volunteer’s knowledge of plants native to this part of rural Pennsylvania,
we purchased 27 (three each for nine groups) plants from
a wholesale nursery, including Aster, foamflower, jackin-the-pulpit, Trillium, Phlox, wild columbine, and wild
Geranium. The total cost for the plants was $51, which
was reimbursed through the science department budget. Then, with stakes, string, scissors, a meterstick, and
hammer in hand, I laid out nine, one-square-meter plots
on the slope.
Preparing Students
First, I tried to find out what students already knew about
soil conservation and erosion. As an introduction I referred to the playing field outside the science classroom,
which was being regraded and resurfaced to prevent
runoff and erosion. The school surrounds this central
field on which the third
through eighth graders frequently play. My students were
aware of the fact that their parents had
recently raised money to regrade the field,
install drainage pipes, and plant grass to prevent
the pooling of water that frequently occurred in the
middle of the playing field. I asked for their predictions:
“Will the project stop the soil erosion?” This led to a
very heated discussion. Several students thought that
the regrading wouldn’t work, because the field still had
a slight slope or because the landscape engineers hadn’t
put walls around the edge of the field. They thought that
the runoff would probably form ditches around the edges, and that the playing field would wear away. Another
student thought that drainage pipes should have been
scattered around the edges of the field instead of having drainage grates scattered throughout the field. Then
I asked if they knew of other ways to conserve soil. After
I showed pictures of several of these methods (see Internet Resource), they recognized terracing and contour
plowing but not grass barriers. Students who had seen
landscaping done at their homes recognized terracing,
and those who had see pictures of farming in developing
countries recognized contour plowing.
As students listed these methods of soil conservations,
I translated their ideas into pictures, which I (or they)
drew on the board (students really enjoyed this way of
learning). I began to explain contour plowing by drawing
a hill and drawing contour lines around it, filling in the
“ditches” with stylized plants. At the top I drew a stick
figure holding a shovel beside a house. For the windbreak
Figure 1.
Soil Conservation Basics.
Soil Conservation: keeping topsoil from washing away
Erosion: topsoil washing away
Terracing: building trenches around the side of a hill
to keep soil from washing away
Runoff: topsoil that washes away after a heavy rain
Contour farming: planting along the slope instead of
up and down
Terracing: holding back water and routing it along a
channel with the contour of a hill to slow the velocity
of water so it won’t run off and take soil with it
Windbreaks: rows of shrubs or trees, which protect soil
from blowing or washing away from rows of crops
Grass barriers: grass or plants planted between rows to
keep moisture in the soil and keep it from blowing away
Clumping: putting groups of plants together in a clump
to retain soil moisture and reduce wind erosion
method, I drew a hill with a house at the top and garden
nearby. A student added trees standing in a row between
the house and the garden.
During this introductory session, I wrote, pronounced,
and gave the definition of the following vocabulary words:
soil, conservation, erosion, terracing, runoff, and clumping
(Figure 1). For the methods with which students were not
familiar (such as clumping and drainage ditches), I showed
magazine or internet pictures (see Internet Resource). Students recorded the information in their science notebooks,
and later I added the words and pictures to a word wall.
Plotting and Planting
Next, I introduced and carefully explained the steps in
the soil conservation activity, in which each group of two
or three students would be responsible for tending onesquare-meter plot of land (Figure 2, p. 46). Each group
would design their plots, choosing three plants and arrange them in the way they thought would best conserve
soil (e.g., spreading them out or clumping them). Students designed their plots choosing one soil conservation method we had talked about in class or created a soil
retention method they thought would work. I checked
these designs to see how clear they were and whether
they were likely to retain soil. Students spent one period
planning the plantings, diagramming, and deciding how
to share responsibilities. Preparing the plots and planting took three successive class periods. The first period
students designed their plots to reflect their method of
soil conservation. After I approved their design, students
prepared their plots the next day. The third day, students
planted their plants according to their plan. Then they
placed a narrow band of masking tape next to the ground
wrapped loosely around the stem of each plant.
Recording Data
The fourth day, students measured the space between
the surface of the ground and the masking tape on the
plant stem and recorded the distance (if any) on their data
sheet. They also noted whether there was rain or wind
since the last measurement. Students were concerned
that the measurement up the stem from the ground
would show stem growth, not soil erosion. However, I
reassured them that plant growth occurs from the tip of
leaves or top of the stem, not from the plant’s base.
The following week, students measured on two successive days and recorded their data. Some plots lost soil over
a couple of weeks, but others stayed the same. One group
of students who had built a mound around each of their
plants found that there was no soil loss. Another group
that took tufts of grass from the land around its plot and
put them between the plants, found that the soil stayed
around the plants. Groups who built ditches around the
outside of its plot seemed to loose soil. This provided an
February 2010 45
Creative Soil Conservation
opportunity to talk about the factors (variables) that might
have affected the rate of erosion. We discussed the various
possibilities. Did the storm, which had blown through on
the weekend, blow away the soil? Did the heavy rain wash
the soil from the top of the slope to the bottom? Could the
markers on the stems have slipped? Did students measure
from the wrong spot on the stem? We concluded that
we could not determine if our plans had conserved soil,
because there were so many factors (variables) that could
have caused the soil to stay in place or erode. There was also
the matter of human error, with some measurements not
collected carefully. This gave us the opportunity to discuss
the importance of accuracy and variables in investigations.
We discussed how we could plan a future investigation in
which we would take measurements more often, plant in
an area protected from mowing or foot traffic, and plant
more robust specimens (instead of seedlings).
Assessments
Student learning was assessed in various ways, including observation and a vocabulary exercise in which students formed sentences using various vocabulary words.
For example, I handed out three cards with vocabulary
words like erosion, terracing, and soil conservation. The
group put their heads together to create a sentence using all of the words correctly. Then they stood in a line in
front of the class in word order and held up their words
as they said their complete sentence. In forming the sentence, the students told me what they knew about the
concepts and the vocabulary words. Then I handed out
three cards to the next group. This is an exercise which
students really enjoy.
Throughout the investigation, I looked for cooperation and sharing of responsibility within groups, how
accurately students were measuring their plant growth,
and how carefully and clearly they were recording their
data. Before the end of the school year, students came
to me between the classes to tell me about the growth
or death of their plants. They became protective and
proud of their plots, showing them off to other students
or teachers. Because the plants were perennials, we
won’t really know how well they did until the following spring.
Loving Science
It was easy to gauge student interest by observing and
listening. As soon as students arrived at my class, they
could not wait to get outside (nor did they want to come
back into the classroom). One shy and conscientious student said to me, “I love doing science this way!”
What was good about this activity is that the thirdgrade students played their part in beautifying the school
with native plants while at the same time learning about
soil conservation. n
Martha Smith ([email protected]) teaches third- through
sixth-grade science at Buckingham Friends School in Lahaska, Pennsylvania.
Acknowledgment
Special thanks goes to parent Geraldine Dougherty for her
help in obtaining native plants and determining suitable plots.
Internet Resource
Best Management Practices to Reduce Erosion
Figure 2.
Instructions.
1.Plan and draw a diagram of how your group will
arrange your soil and where you will put the plants
to best conserve soil. Have your plan approved by
your teacher.
2.Decide how to share responsibilities for preparing
the soil and planting.
3.Prepare the soil in the plot with a trowel or large
spoon (turn over the soil, dig trenches or holes
about 10 cm deep in the places where the plants
will be, based on your plot diagrams.
4.Plant the plants. Wrap a thin piece of masking tape
around each stem 2 cm up from the ground. (This is
how you will measure soil erosion.)
5.Clean up and return materials. Wash hands
well after handling plants and soil.
6.Record the names of each of your three
plants on the data sheet.
46 Science and Children
www.epa.gov/oecaagct/ag101/cropsoil.html#bmps
Connecting to the Standards
This article relates to the following National Science
Education Standards (NRC 1996):
Content Standards
Grades K–4
Standard A: Science as Inquiry
• Abilities necessary to do scientific inquiry
Standard C: Life Science
• Organisms and environments
Standard F: Science in Personal and Social
Perspectives
• Changes in environments
National Research Council (NRC). 1996. National
science education standards. Washington, DC:
National Academies Press.