vit
acti ies
32&33 Plants and Sunlight
(Sessions I and II)
BROWARD COUNTY ELEMENTARY SCIENCE BENCHMARK PLAN
Grade 3—Quarter 4
Activities 32 & 33
SC.B.1.2.1
The student knows how to trace the flow of energy in a system (e.g., as in an ecosystem).
SC.B.2.2.1
The student knows that some source of energy is needed for organisms to stay alive and
grow.
SC.H.1.2.1
The student knows that it is important to keep accurate records and descriptions to provide
information and clues on causes of discrepancies in repeated experiments.
SC.H.1.2.2
The student knows that a successful method to explore the natural world is to observe and
record, and then analyze and communicate the results.
SC.H.1.2.3
The student knows that to work collaboratively, all team members should be free to reach,
explain, and justify their own individual conclusions.
SC.H. 1.2.4
The student knows that to compare and contrast observations and results is an essential
skill in science.
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SC.H.3.2.2
The student knows that data are collected and interpreted in order to explain an event or
concept.
ACTIVITY ASSESSMENT OPPORTUNITIES
The following suggestions are intended to help identify major concepts covered in the activity
that may need extra reinforcement. The goal is to provide opportunities to assess student
progress without creating the need for a separate, formal assessment session (or activity) for
each of the 40 hands-on activities at this grade level.
1. Session I—Activity 32: Ask students if they know of any plants that grow in total
darkness. (There are none.) Ask if they know of any plants that grow in heavy or moderate
shade. (Some do, such as impatiens.) Have students predict and draw a picture of what
they think their planting pot will look like after one day, three days, six days and nine
days. Just before starting Activity 33 have them verify their predictions.
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2. Session II—Activity 33: Ask the students if the predictions they made above were close to
what actually occurred. (They should report some general accuracy.) Ask, If humans need
energy to survive, do you think plants do, too? If so, where do you think they get their
energy? (Yes, plants need energy. They get that energy from sunlight.) Follow-up by asking
them to list evidence of the Sun’s role in helping plants grow, as they saw it in this
investigation. (The plants that got less sun grew less.)
3. Use the Activity Sheet(s) to assess student understanding of the major concepts in the
activity.
362
activities 32 & 33 Plants and Sunlight
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In addition to the above assessment suggestions, the questions in bold and tasks that
students perform throughout the activity provide opportunities to identify areas that may
require additional review before proceeding further with the activity.
vit
acti ies
32&33
Plants and Sunlight
2 bags
1
6
1 roll
OBJECTIVES
Students grow plants with varying amounts
of sunlight to learn that plants need a
source of energy to stay alive and healthy.
The students
plant grass seed
monitor plant growth in different growing
conditions
determine that plants need sunlight to stay
alive and healthy
soil, potting
spoon, measuring (Tbsp)
sprinkler bottles
tape, masking
water, tap*
Delta Science Reader Food
Chains and Webs
*provided by the teacher
PREPARATION
Session I—Activity 32
SCHEDULE
1
Set up a distribution station with the
following items: six flowerpots, six plastic
trays, six sprinkler bottles filled with
water, one bag of grass seed, two bags
of gravel, two bags of potting soil, a
measuring spoon, and a roll of masking
tape. You may want to cover the table with
newspaper first for easy cleanup. Have
paper towels on hand for spills and hand
washing.
2
Find a warm, sunny spot where students
can keep their flowerpots while the grass
seeds sprout (about a week).
3
You will need a sheet of plastic to cover
the pots during germination.
Session I—Activity 32 About 30 minutes,
followed by regular maintenance for 1 week or
until the grass shoots are about 8 cm (3 in.)
tall
Session II—Activity 33 About 15 minutes,
followed by daily observations for 2 more
weeks
MATERIALS
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For each student
1
Activity Sheet 32
1 pr
safety goggles*
For each team (6 teams total)
1
1
flowerpot
tray, plastic
For the class
1 pkg grass seed
2 bags gravel, large
newspaper*
1 roll
paper towels*
1
plastic sheet, large
Session II—Activity 33
1
Make a copy of Activity Sheet 32 for each
student.
2
Find a dark place where Teams 4, 5, and 6
can keep their flowerpots for 2 weeks.
Keep in mind that students will need
access to the pots every day.
3
Each team will need their flowerpot from
Session I. They also will need sprinkler
bottles of water.
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363
At the end of the experiment, set up an
observation table in the classroom
where students can observe all six pots
of plants side by side.
BACKGROUND INFORMATION
There are hundreds of thousands of plant
species on Earth, thriving in a variety of
growing conditions. All plants, regardless of
where they grow, need sunlight, water,
nutrients, and air (oxygen and carbon
dioxide, among other gases). Without these
basic elements, plants cannot survive.
4
Activity Sheet 32
Plants and Sunlight
Session I—Activity 32
Team
Light
How Plants Look
(Before)
How Plants Look
(After)
1
sunlight
healthy
healthy
2
sunlight
healthy
healthy
3
sunlight
healthy
healthy
4
darkness
healthy
unhealthy
5
darkness
healthy
unhealthy
6
darkness
healthy
unhealthy
1. Which plants do you think will grow better? Which do you think will grow
In this activity, students observe the effects
of variations in sunlight on the health of
plants. They discover, for example, that
plants that are deprived of sunlight become
pale and spindly. Plants contain a chemical
in their leaves and stems called chlorophyll.
Chlorophyll is a pigment that gives plants
their green color. When activated by
sunlight, chlorophyll enables the plant to
make its own food. Without sunlight, a
plant literally “starves.”
worst?
Predictions will vary.
2. Which plants look better? Were your predictions correct?
Plants grown in sunlight look the best.
3. What do plants need in order to grow and stay healthy?
sunlight
Over millions of years, plant species have
adapted to the conditions in which they
now grow. Any change in growing
conditions can slow or stunt the growth of a
plant. It can also weaken the plant, making
it susceptible to disease. However, those
plants that are not weakened continue to
thrive and reproduce new generations of
hardy plants.
364
activities 32 & 33 Plants and Sunlight
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Plants combine water (H2O) and carbon
dioxide (CO2) from the air to produce
glucose (C6H12O6). This process, known as
photosynthesis, can take place only in the
presence of both light and chlorophyll.
Guiding the Activity
Additional Information
Session I—Activity 32
1
Divide the class into six teams and assign each
team a number from 1 to 6. Give each team a
plastic flowerpot and a piece of masking tape
to label their pot with their names and team
number. Then have them gather around the
distribution station. Supervise students as
they work together to plant the grass seed, as
follows (see Figure 32-1):
1. Put a thin layer of gravel at the bottom of
the pot.
2. Fill the pot with potting soil to within 3 cm
(1.2 in.) of the top.
3. Sprinkle 2 tablespoons of grass seed
evenly over the surface of the soil.
4. Sprinkle a final, thin layer of soil over the
seeds.
5. Pat the surface of the soil gently.
6. Place the pot on a plastic tray.
7. Water the soil generously.
8. Place the pot in a warm, sunny spot.
To increase student participation, have each
member of the team be responsible for one
of the planting steps while the rest of the
team gives help as needed.
thin layer of soil covering seeds
2 Tbsp. grass seed
sprinkled over soil
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Cover all six pots with a sheet of plastic. Have
a different student volunteer lightly water all
of the pots every day. Within 3 or 4 days, the
surface of the soil will swell and crack. A day
or two later, green grass shoots will poke
through. Remove the plastic at that time. In
about a week or so, the shoots will be about 8
cm (3 in.) tall. Then begin Session II.
Clean up the distribution station. Discard the
newspaper. Seal the bags of leftover gravel,
soil, and grass seed and return them to the
kit. Have students wash their hands.
flower pot
gravel
potting
soil
plastic tray
Figure 32-1. Planting grass seed.
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365
Guiding the Activity
Additional Information
Session II—Activity 33
2
When the shoots are about 8 cm (3 in.) tall,
have each team retrieve its pot of grass. Have
students examine the plants. Ask, What do
you think plants need in order to grow?
Accept all reasonable responses.
Write the term growing conditions on the
board and read it aloud to students. Tell
students the amount of light and water a
plant receives, the type of soil it is planted in,
the temperature of the air, and other factors
that affect plant growth are called growing
conditions—the conditions in which the plant
grows.
Ask, How can you tell if a plant is receiving
the right amount of light?
You could change the amount of light it
receives—change its growing conditions—
and see what happens to the plant.
Tell students that groups are going to grow
their pot of grass in different growing
conditions to learn what the plants need to
stay healthy.
Distribute a copy of Activity Sheet 32 to each
student.
Have students observe the appearance of the
plants in their pot and record the information
in the column labeled How Plants Look
(Before). Then have Teams 1, 2, and 3 place
their pots in a sunny spot. Have Teams 4, 5,
and 6 place their pots in a dark place. Tell
students that they will give their plants 8
ounces of water once a week. (One sprinkler
bottle holds 8 ounces.)
Tell students that each team will be
responsible for maintaining its own pot of
plants. Students are to observe their plants
every day.
Ask students to predict which pots will fare
better and why. Tell them to record their
predictions on the activity sheet.
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activities 32 & 33 Plants and Sunlight
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3
Guiding the Activity
4
After 2 weeks, have students review the
condition of the plants. Place the plants on a
table where all students can see them. Have
students compare the appearance of the
plants and record their observations in the
column labeled How Plants Look (After) on
the activity sheet.
5
To help students understand the significance
of their observations, ask, What differences
did you notice between the plants that
were in sunlight and those that were in
darkness?
Ask, How can you explain these differences?
Additional Information
The plants that were in sunlight are green
and healthy-looking. The ones in darkness
are pale and tall and spindly, or didn’t
grow at all.
Students should suggest that sunlight must
be something that plants need in order to
grow.
Explain to students that sunlight contains
energy, and plants use this energy to make
food. The plants use the energy in the food
they make to live and grow.
6
Tell students that all organisms need a source
of energy to live and grow. Ask, Where do
you get the energy you need to live and
grow?
Remind students that some foods they eat
come from plants. Ask, When you eat foods
that come from plants, where did the
energy that you take in originally come
from?
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7
Students should understand that they get
their energy from the food they eat.
Students should see that the plants use
the energy of the sun to make food, and
when they eat the plants they are getting
energy that originally came from the sun.
As appropriate, read or review pages 6–9 of
the Delta Science Reader Food Chains and
Webs.
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367
REINFORCEMENT
Have students repeat the activity, using light
conditions of their own choosing. They might
want to discover, for example, whether grass
plants grow better in partial sunlight or full
sunlight.
SCIENCE JOURNALS
Have students place their completed activity
sheets in their science journals.
SCIENCE AT HOME
Encourage students to volunteer to care for
houseplants at home. Do all the plants in
their homes need the same amounts of
sunlight? What other activities to they do to
take care of houseplants? (remove dead
leaves or flowers, repot when a plant gets
large, add plant food) They could also take
two plants of the same kind, grow them in
different conditions, and compare the
results.
CLEANUP
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activities 32 & 33 Plants and Sunlight
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Have students correct the sunlight conditions
of the pots so that the plants do not die. You
may want to save the pots of grass for
further experimentation. To “mow” the grass,
simply trim the leaves with scissors. Discard
the cuttings outdoors.
Connections
Science Challenge
Science and Math
Strictly speaking, plants need light, but not
sunlight specifically, to produce chlorophyll
and carry on photosynthesis. Suggest that
teams design and conduct their own
experiments to determine whether artificial
light from different types of light bulbs would
produce plants as healthy as plants grown in
sunlight. Students might like to try an
ordinary incandescent bulb, a red bulb, a
yellow “bug light” bulb, an ordinary
fluorescent bulb, and a “gro-lite” bulb
intended specifically for house plants. Remind
students to control all other variables,
including the type of plants used, the amount
of water they are given, and the amount of
time they are exposed to light each day. When
students have completed their experiments,
let the teams share their experimental
designs, results, and conclusions in a class
discussion. Have students research each type
of bulb used in the experiment and report on
the makeup of each.
Tell students that only 2% of the sunlight that
reaches Earth is available to plants for
photosynthesis. About 50% of the sunlight is
reflected back into space by clouds and dust
in Earth’s atmosphere, about 20% is
absorbed by the atmosphere, and about 28%
heats the land and water. Help students make
a pie graph showing these proportions.
Science, Technology, and Society
Obtain (or have students bring from home)
labels or care directions for various
houseplants. Have students note differences
in the amount of sunlight different kinds of
plants need. Discuss why some plants need
more sunlight than others, and help students
see the connection between the environment
where the plant lives in nature and the
amount of light it needs in a home.
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Science Extension
Tell students that different kinds of plants
need different amounts of water. To show
this, set up three houseplants that need
different amounts of water: for example, a
fern or coleus, which needs evenly moist soil
plus occasional misting; a pothos or
geranium, which can be allowed to dry out
before rewatering; and a cactus or other
succulent, which needs only infrequent
watering in small amounts. Let students take
turns watering the three plants so they can
see how much each requires and when.
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activities 32 & 33 Plants and Sunlight