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Photosynthesis
and transpiration
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Grade
Level: 6-8
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Overview
It has been found that many students are not interested in
science. They often think that the concepts taught in science are irrelevant
to their needs. They think that science is boring and difficult. Until
children experience science in a fun way, their attitude toward science
won't change. Let all teachers try to win more children for Science. Plants
provide a renewable source of food energy for many forms of life. Green
plants utilize the sun's energy and the gases in the atmosphere to produce
food through photosynthesis and exchange gases in the atmosphere in the
associated process of transpiration.
Purpose The purpose of this lesson is to help students experience
science in a different way, and to change students negative attitudes
toward science into positive ones.
Objectives
Students will be able to:
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| i. Observe the effect of light on
plants. |
| ii. Illustrate the exchange of gases
between the atmosphere and the plant. |
| iii. Describe how green plants use
the sun's energy to produce food through photosynthesis. |
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iv. Show that plants are part of many natural cycles.
Resources/Materials
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| Two or more six inch pots, |
| Fifty or more pea seeds, |
| Potting soil, |
| A sprinkler (a jar with holes in
the lid), |
| A dark area (a large cardboard box)
or a cabinet, |
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Glass bottle or jar, Paper, pencils, crayons
Activities
and Procedures
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| i. Have the class divide into small
groups (if not conducting this experiment as a demo.) Have each student
make an illustrated log of events for germination of the seedlings to the
end of the experiment. |
| ii. Germinate pea seeds by placing
them onto damp paper towels in a tray or shallow dish and covering them
with warm tap water. Keep covering them with warm tap water. Keep covered
with warm water and in an indirectly lit place. A "hook" should appear in
two to three days. After the "hook" appears, the seeds are ready to be planted
in the pots. |
| iii. Prepare two pots by placing
paper towels as a lining for each pot. Fill with the vermiculite soil mixture
up to 2 1/2 inches from the top. |
| iv. Place the seeds carefully on
top of mixture. Cover with 1/4 to 1/2 inches of soil mix. |
| v. Sprinkle water over the top of
the soil until the soil is well saturated. |
| vi. Place one of the pots in a well
lit place. |
| vii. Place the other pot in the designated
dark area and leave it completely in the dark for one week to ten days. |
| viii. At the end of one week or ten
days, remove the pot from the designated dark area and compare it with the
pot of seedlings that were grown in the light. |
| ix. Have the class discuss the differences
and make a drawing to illustrate the differences between the two sets of
seedlings. |
| x. Leave the pot that was in the
dark in the light for a few days, and compare the results. |
| xi. Remove one seedling from each
pot and compare the root structure of the dark grown seedlings and the light
grown seedlings. |
| xii. Place a glass bottle over one
of the seedlings, and place it in the sunlight. |
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xiii. Notice the condensation that occurs on the inside of the bottle.
The condensation is water vapor being given off by the plant when it exchanges
oxygen for carbon dioxide. (transpiration)
EXTENSIONS
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| 1. Take the class out to a grassy
area on the school grounds. Dig up a shovel full of grass covered soil.
Have the class examine the depth of the roots and their structure. How do
they differ from the pea seedling roots? How does grass differ physiologically
from the pea seedlings? (Stems, leaves, etc.) Do they have the same photosynthetic
process? |
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2. Take the class to a treed or forested area. Compare the effect of
light on identical seedlings growing in the shade of a tree and seedlings
growing in sunlight.
Tying
it all together This activity shows vividly, the conditions
necessary for germination of good seeds. Let the children learn and recite
this Poem.
Title: Plant Growth
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| Weak
weak tiny plant |
| Why look so lean and feeble |
| Inside a box so dark? |
| I look so lean |
| I feel so weak |
| For I need three things for life: |
| Air, sunshine and water |
| But Tosan fed me only two. |
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ELSSA, 1997
Assessment
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| 1. From the series of activities,
let the children list in their note books the conditions necessary for germination
of good seeds |
| 2. Let each child recite before the
class, the Poem on Plant Growth. |
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3. Encourage the children to recite the Poem at home to their family.
Suggestions/Modifications
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- Students may draw and graph the progressive growth of the sunlight
plant as it takes shape.
- Students may draw the plants they have in and around their homes
and research the names of the plants.
- Students may invent fictional plants which may have medicinal, magical,
or special powers.
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Author(s)
Nelida Boreale, Mountain View Elementary, AZ
http://www.col-ed.org/cur/
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