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Breathing Plants: Grades K-4
Breathing Plants
Educational Activity: Grades K-4
Time: One 30-minute class period (followed by 20 minutes for
observation every 3 days for three weeks)
Overview:
In this activity, students discover how plants breathe through their leaves. Note: This
lesson, Breathing Plants, is one in a series of lessons introducing basic plant parts and
functions. Other lessons cover flower anatomy, seed function and dispersal, movement of
water in stems, and root structure and function.
Integration with Project BudBurst
Elementary school students participating in Project BudBurst study plants in their
schoolyard environment and learn to make careful observations of the timing of leafing,
flowering, and fruiting of selected plants. In conjunction with teaching students to make
observations of living plants, teachers may also introduce basic plant anatomy, a topic
typically covered at this age. The lessons in this series on plant parts and function may be
used as an introduction to participation in Project BudBurst, to help set the stage for what
students will be observing. Alternatively, teachers may use these lessons in between
times students make outdoor observations to extend their understanding of what they are
observing. For example, as students observe flowering, teachers may use the lesson
Operation Flower Dissection to help students understand the structure and function of
flowers. Similarly, as students observe leafing, teachers may use this lesson Breathing
Plants to introduce leaf function.
Learning Outcomes:
Students will be able to:
 Identify the part of the plant where ‘breathing’ occurs (in terms of gas exchange with
the air)
 Describe differences between leaves coated with Vasoline to prevent ‘breathing’ and
uncoated leaves.
budburst.org
A Project BudBurst Educational Activity
http://www.budburst.org/educators/pdf/PBB_breathingplants.pdf
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© 2016 Chicago Botanic Garden. All rights reserved. One of the treasures of the Forest Preserves
of Cook County.
Breathing Plants: Grades K-4
Materials:
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Geranium or other potted plant
Adhesive labels
Vaseline
Cotton swabs
Education Standards: Available at:
http://budburst.org/educators/breathingplants_sg.php
Activity
1) Explain to students that plants breathe through their leaves. During the day, when
plants are using sunlight to make sugars in their leaves (i.e., photosynthesis), they
take in carbon dioxide and let out oxygen (which is just the opposite of animals). At
night, when they are not making sugars, they take in oxygen and let out carbon
dioxide from respiration.
2) Tell students they are going to investigate the question “How do plants breathe?” in
this activity. They will observe differences in plants with their leaves intact and plants
with their leaves coated so that gases cannot enter or exit the leaf.
3) Use Vaseline to coat three plant leaves like this:
 Top of one leaf
 Bottom of one leaf
 Both top and bottom of one leaf
4) Be sure there is at least one other leaf on the plant with no coating.
5) Label the leaves with “top,” “bottom,” and “top and bottom”
6) Put the plant in a sunny location and water regularly. Have students observe the plant
for three weeks and record their observations.
7) After three weeks, have the students explain what has happened to each of the three
leaves, and compared with other uncoated leaves. Did all of the coated leaves
change? What does this tell us about how plants breathe?
Suggested Extension Activities
 Prevent a plant from photosynthesizing. Place masking tape on approximately half of
a leaf’s surface. Leave the plant in the sun for several days. Return and remove the
tape. The leaf has changed colors because it can no longer photosynthesize and does
budburst.org
A Project BudBurst Educational Activity
http://www.budburst.org/educators/pdf/PBB_breathingplants.pdf
Page 2 of 4
© 2016 Chicago Botanic Garden. All rights reserved. One of the treasures of the Forest Preserves
of Cook County.
Breathing Plants: Grades K-4
not need the chlorophyll to give it its green color.
 View transpiration in action. Affix a sandwich baggie to a leaf. Leave it in the sun for a
couple of hours. Return to view moisture which was transpired through the leaves and
condensed on the inside of the bag.
 Ask students to consider how plants and animals/people need each other to breathe.
What happens when big forests are cut down, such as tropical forests in Southeast
Asia and South America?
 Make crayon rubbings of various leaves collected from outside. Compare the location
of the veins in the leaves. Monocots will have parallel veins, whereas dicots will have
net-like veins.
Background Information
Leaves are the parts of the plant where food is made by photosynthesis. Leaves take in
carbon dioxide from the air, water from the soil, and energy from the sun. During
photosynthesis, the leaves use light energy to change carbon dioxide and water into
sugars (food). The leaf is also where respiration, or “breathing” (in terms of gas
exchange), takes place. Respiration is the opposite of photosynthesis. It is the process in
which plants convert sugars into energy, using oxygen. In respiration, plants take in
oxygen from the air and release carbon dioxide.
A leaf contains long strips of vascular tissue called veins. These supply the leaf with water
and minerals, and move the food made inside the leaf to other parts of the plant. Some
leaves, such as grasses, have long, parallel veins, but most leaves contain one central
vein called the midrib. This is an extension of the leaf stalk, which joins the body of the
leaf to the stem. The midrib branches into a number of smaller veins, called side veins. A
leaf’s whole vein system is called its venation.
Water is taken into a plant by its roots, and travels up through the stem to the leaves.
There, some of it escapes as vapor through tiny holes called stomata on the underside of
the leaves. This type of water loss is called transpiration.
Student Assessment Suggestions:
Teachers may have students make drawings depicting their understanding of the location
of breathing in plants.
Source: Adapted from Exploring the Native Plant World, developed by the Lady Bird
Johnson Wildflower Center in Austin, Texas and Teaching Plants from Root to Seed,
developed by the Denver Botanic Gardens in Denver, Colorado.
budburst.org
A Project BudBurst Educational Activity
http://www.budburst.org/educators/pdf/PBB_breathingplants.pdf
Page 3 of 4
© 2016 Chicago Botanic Garden. All rights reserved. One of the treasures of the Forest Preserves
of Cook County.
Breathing Plants: Grades K-4
This teacher resource was made possible, in part, by support from the National
Geographic Education Foundation.
budburst.org
A Project BudBurst Educational Activity
http://www.budburst.org/educators/pdf/PBB_breathingplants.pdf
Page 4 of 4
© 2016 Chicago Botanic Garden. All rights reserved. One of the treasures of the Forest Preserves
of Cook County.