photosynthesis experiment for preschoolers

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Last updated by Linda Kamp on December 9, 2022 • 2 Comments

Breathing Leaves Photosynthesis Experiment for Kids

When we discuss the importance of plants in nature in second grade, it can be hard for students to fully grasp plants’ ability to create oxygen for us to breathe. This simple photosynthesis experiment is a great opportunity for hands-on learning in any Plants, Animals, & Life Cycles science unit.

How do plants create oxygen?

Plants release oxygen that all living things need. Plants also clean out air and absorb harmful pollutants through their leaves. This makes plants extremely important for other living things to survive on Earth.

As we breathe, the air we inhale is 21% oxygen. After we breathe in oxygen, we exhale carbon dioxide. Carbon dioxide is needed by plants for them to survive. Plants use carbon dioxide and sunlight to help them make oxygen. Leaves convert sunlight into energy as part of a process called photosynthesis. As the leaf takes in sunlight to create that energy, it expels, or breathes out, oxygen. But how can we see oxygen? Can plants produce oxygen without sunlight?

Think about when you are underwater holding your breath. If you release a little bit of air, you see bubbles. In this activity, students will observe a leaf using sunlight to create oxygen. Students will do a  demonstration using leaves in water to help them see the oxygen a leaf expels, or breathes out.

Pose this question to students to help introduce the lab: How can you see a plant creating oxygen?

The changes that take place in this lab activity occur over a 1-2 hour period, so make sure to plan for that ahead of time. I have found that it works for me to set up the lab in the morning and check it after lunch.

Easy photosynthesis experiment

• clear plastic cup or bowl
• fresh leaves
• small rocks

Place students in groups and pass out two cups of water, two fresh leaves, 2 small rocks, a hand lens, and a lab sheet.

Students place a leaf in a clear cup of water. Then, they place the other leaf in the other cup of water. Put one of the cups in a sunny spot and one in a dark spot.

Place a small rock on the leaf to keep it completely submerged in water.

After about 20 minutes, you will see tiny bubbles begin to form on the edges of the leaf. Many float upwards and stick to the side of the cup.

For a better look, students should use a hand lens to observe the bubbles. Explain to students that the small air bubbles are oxygen released by the leaf. The leaf remains active for a couple of hours. The process of photosynthesis will continue for a while if the cup is placed in the sun. During this process, the leaf expels oxygen into the water, which caused bubbles to form.

Students should check the cups every 30 minutes and record changes to both cups on their lab sheets. Ask students: “Which leaf produced the most oxygen? How can you tell?” Students should notice that the leaf that produced more oxygen has more bubbles.

Next, ask: “Why did one leaf produce more oxygen than the other leaf?” Guide students to notice that the leaf in the dark did not have sunlight, so it did not produce as much oxygen. A fresh leaf will remain “active” and still convert sunlight to energy and release oxygen for several hours.

Have students complete the questions on their lab sheets to consolidate their knowledge and make interpretations about the lab’s outcome.

Finally, discuss how this lab shows the importance of plants to animals. Besides food, what do plants provide for animals?

More Plants, Animals, & Life Cycles experiments and lesson plans

This photosynthesis experiment is perfect for helping students better understand the process of leaves producing oxygen. It’s an amazing way for students to really see the process of photosynthesis at work!

This fun photosynthesis experiment is part of a complete  Plant and Animal Needs, & Life Cycles unit for 2 nd grade that is also available in a digital format with narrated lesson slides.

Click here to see the yearlong 2nd grade science series.

Pin this photosynthesis experiment for later so you have it when you teach about plants!

Click on these these pictures for more hands-on science activities:

Happy teaching!

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August 15 at 10:16 am

Hi , is this lab sheet available for purchase on its own?

August 21 at 8:38 am

Hi Sarah, Thanks for reaching out! Unfortunately, I don’t have any of the labs available separately.

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I’m Linda Kamp, a 20 year primary grade teacher with a passion for creating educational materials that excite students and make learning fun! I'm so glad you're here!

How Do Leaves Breathe? A Simple Science Experiment for Kids

By: Author Jacquie Fisher

Posted on Published: September 22, 2022

Categories Educational Activities , Nature & Outdoor Activities , Science Experiments

I just realized that we haven’t shared many Simple Science Experiments lately. Our goal with Simple Science activities is to provide you with quick & easy ideas that help kids explore science! 

For today’s experiment, we’re going to head outside and learn how leaves and trees breathe!

How Do Leaves Breathe? A Simple Science Experiment

Most of our simple science experiments require very few items (many of which are found around your home) and can be set up in less than 5 minutes. If you’d like to introduce your child to science, these experiements are the perfect place to begin!

All you’ll need for this experiment is a bowl of water and a leaf!

We’re going to create an environment where we can actually SEE photosynthesis taking place — the oxygen/carbon dioxide process of plants! 

While you don’t need many supplies for this activity, we have listed affilite links for books and a few items that we found helpful during the experiment and to expand on the learning opportunity.

This activity is really VERY interesting for two reasons:

• first, kids don’t always think of plants & trees as ‘living’ things so this helps them to visualize that concept and

• second, it’s a way to actually SEE something that is normally invisible!

Before you begin the experiment, we suggest introducing the topic with a book.  Here are a few books we highly recommend:

Tell Me, Tree: All About Trees for Kids and A Tree is a Plant (Let’s Read and Find Out Science)   for preschool and elementary age kids.  Both books give a nice overview of the lifecycle of a tree including science terms.

For a more in-depth science look, try Botany: Plants, Cells and Photosynthesis (Super Smart Science) for middle schoolers or if you’re looking for LOTS of great answers to botany science questions, see V is for Venus Flytrap: A Plant Science Alphabet !

If you’re also studying plant cells as part of a biology unit, the Learning Resources Cross Section Plant Cell model or the 4D Plant Cell model are both awesome teaching tools for this concept!

Exploring How Plants and Trees Breathe

Even though we chose to use a tree leaf, you can also conduct this experiment using a leaf from a plant — the important step is including an ACTIVE leaf (meaning one that you remove from the tree or plant).

Step 1:  Fill a large bowl with lukewarm water

You can use a glass or plastic bowl (personally, I like glass bowls better as you’ll be able to see the experiment from all angles however you will probably have the bowl outside so you may want to use plastic).

If you’re replicating this experiment in the classroom, a large size beaker would also work — in fact, you can extend the experiment by measuring the amount of water you use to cover the leaf to see if that has any impact on the results!

I have not tried this experiment with a metal bowl so if you do, send me a note and let me know how it turns out!

Step 2:  Head outside and find a large leaf

You’ll want to remove a leaf from a tree or plant and not just pick one up off the ground as we want an ‘active’ leaf for the project.  I know — if you’re like me, you probably tell kids not to pull the leaves off trees (which is a good rule to follow) but for this experiment, carefully remove a leaf.  If you’re doing this with a group, have kids pair up if you’d like so not as many leaves are needed.

You can also use the leaf to have some fun with art & science by making a leaf rubbing once you complete the experiment!

Step 3:  Place the leaf in the bowl of water and put a small rock on top of it so it is FULLY submerged under the water

You should do this right away.  Don’t let the leaf sit around too long before submerging it in water. Then place the bowl in a sunny spot – outside in direct sunlight is best.

As you can see, this is really the benefit of using a glass bowl — you can be sure your entire leaf is underwater.  If you have a place inside that’s super sunny, you can also try keeping the bowl there.

Step 4:  WAIT!

Oh yea, did I mention that now we need to wait a few hours 😉

I know — one of the hardest things for kids.  So go on with your day — maybe set the experiment up before lunch.  Or your kids can get it ready before they head off to school or the park and it will be waiting for them when they come back.

While you’re waiting, kids can explore the science, math, art and nature of leaves with our *NEW* Leaf STEAM Printable Pack which includes 7 hands-on STEAM activities — create leaf rubbings, make chlorophyll prints, learn the parts of a leaf, construct a leaf graph & more!

Or try one of these other simple science experiments:

Does your Food Sink or Float?   {physics & density for kids}

Create Your Own Gong ! {science of soundwaves for elementary & middle school}

How Much Water is in Snow? {evaporation & weather science}

Step 5:  Take a peek a few hours later

What you should be seeing is small bubbles that form around the leaf and the edges of the bowl.  These are easy to see with the naked eye but having a large magnifying glass on hand always makes an experiment feel more scienc-y 😉

Explaining Photosynthesis & Respiration for Kids

Ask your kids what would happen if they held their breath, went underwater in the pool and then let their breath out — they would see bubbles coming up in the water.

That’s what they are seeing here — the leaf is still using the sunlight as part of the photosynthesis process (where leaves convert sunlight to energy). 

As a leaf creates that energy, it needs to get rid of the items it no longer needs so it will expel both the extra oxygen during  photosysthesis along with water (the release of water from a plant is called transpiration). 

The process of photosynthesis is what allows us to see the bubbles — as the leaf releases its’ extra oxygen while submerged, the oxygen can be seen as bubbles in the water. And since oxygen is lighter than water, the bubbles will eventually rise to the surface.

Related Activity: Name that Tree! Leaf & Seed Identification

Why does a plant need oxygen?

Now, does a tree or plant breathe the same as we (humans) do?

A plant, tree or leaf doesn’t have any lungs or respiratory system. But it is a living organism just like we are!  It takes in air through their stomata.

A human takes in air with oxygen and as they exhale, they release carbon dioxide.

Plants take in carbon dioxide from the air and then release oxygen as photosynthesis and respiration occur.

So there you have it — you can tell the kids they are ‘seeing the invisible’ because when leaves are on the tree, you aren’t able to really see the process of photosynthesis in the works 😉

If you’re looking for more plant science ideas, try using a Garden Root Viewer to see how plants grow or use this set of Printable Science Botany Activities to extend the learning !

More Leaf Science Experiments

Here are a few more leaf activities you’ll enjoy —

18 Fall Leaf Crafts & Experiments

Using Leaf Rubbings to Study the Parts of a Leaf

More Simple Science Activities

Looking for more easy science experiments?  Try these!

Dissecting a Flower

12 Citizen Science Projects for Kids

20 Science Experiments you can do in a Jar

Photosynthesis Experiments for Kids

Photosynthesis is the process by which plants convert energy from the sun into the energy they need to survive. In an introductory biology class, students will learn about plant photosynthesis and can find ways to observe it in their everyday lives. Photosynthesis experiments offer students the chance to understand the photosynthetic process, plant biology and the scientific method.

Plant Cover-up

For young students just beginning to learn photosynthesis, an experiment covering up a plant's leaves demonstrates basic concepts. For this project, students should have a plant with large leaves, such as a philodendron or an English ivy; cutouts of construction paper; and paper clips. After clipping the paper to individual leaves, students should wait a few days to observe the effects. Each plant should be placed where it will receive significant sunlight. Ideally, students should observe two plants: one with clipped leaves and one without. After a week or two, students will notice which plant was better able to photosynthesize.

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Ideas for controlled-variable science projects, a science project for growing plants with coffee grounds or soil, simple experiments for the relationship between diffusion & temperature, evaporation lessons & activities for third grade, science experiment with rocks that absorb water, oxygen creation.

Students should conduct experiments to learn that the photosynthetic process creates oxygen. To begin, students should remove a single leaf from a broad-leaved plant and place the leaf in a clear bowl of water set in a sunny spot. After an hour, students can return to the bowl and observe the area around the leaf. They should notice small bubbles -- the oxygen released from the leaf through photosynthesis. Students can conduct the same experiment in a dark location and compare the results.

Importance of Surface Area

The surface area of leaves allows the plant to have access to the sun and helps plants convert light energy into oxygen. To demonstrate the importance of surface area, find two identical small plants that are alive and healthy -- ideally plants with large leaves. After cutting all the leaves off one plant, the students should leave both plants in the sunlight and water them for two weeks. At the end, they can observe the two plants and consider which thrived best in the two-week period.

Photosynthesis and Pigments

In the fall, leaves change color because of reduced sunlight. Students, however, can accelerate this pigmentation process in a simple experiment that extracts colors from leaves. To begin, they should collect green plant leaves from different trees, particularly those known for vibrant colors, such as maples. The leaves should be torn up, placed in glass beakers and covered with rubbing alcohol. The beakers are then placed in hot tap water for about 30 minutes or until the rubbing alcohol turns green from the leaf pigments. Students can then cut narrow strips from a white coffee filter and tape one end of each to a pencil. The filters should be suspended so they are just touching the surface of the alcohol in each beaker. The moisture will travel up the filters and reveal each leaf's changing colors as the pigments break up.

• Kids Fun Science: Plant Experiments Creating Oxygen

Kevin Wandrei has written extensively on higher education. His work has been published with Kaplan, Textbooks.com, and Shmoop, Inc., among others. He is currently pursuing a Master of Public Administration at Cornell University.

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Steps of Photosynthesis for Kids

All living organisms need energy to live on earth. People get energy by eating food. But how do plants get their food? Green plants make their own food and food for us through the process of photosynthesis. Here’s a simple and fun way to introduce photosynthesis for kids. Check out more plant experiments for kids !

What is Photosynthesis?

The meaning of the word “photosynthesis” is the combination of two words, “photo” which means light, and “synthesis” which means putting together.

Photosynthesis is the process plants use to make their own food. There are four main things plants need for photosynthesis to take place, sunlight, chlorophyll, water, and carbon dioxide gas. Plants get water from the soil when it rains and carbon dioxide from the air.

What does photosynthesis produce? Photosynthesis results in oxygen and glucose (sugar). The oxygen is released into the air. The plant uses some of the glucose and the rest is stored.

Where does photosynthesis happen? The process of photosynthesis occurs in the leaves of plants, specifically in organelles called chloroplasts . This is where light energy is able to be converted into chemical energy, and is an example of a chemical change .

Chlorophyll are green pigments that give plants their green color. You will find chlorophyll in the chloroplasts and they help plants absorb the energy from the sun.

Photosynthesis Process Step By Step

Photosynthesis occurs in two stages: a light-dependent stage during the day and a non-light-dependent stage that can occur at any time.

Light-dependent photosynthesis reactions occur in the chloroplasts, where chlorophyll and oxygen absorb the light produced.

The Calvin Cycle’s second stage occurs in the leaves’ stoma. It uses energy from the previous reactions to make glucose from CO 2 .

Photosynthesis is a great example of a chemical reaction or change because new products, glucose and oxygen, are formed.

Why is Photosynthesis Important?

Without the process of photosynthesis, very few organisms could live on earth. Plants use the carbon dioxide that is a by-product of respiration and in turn release oxygen into the atmosphere for us to breath.

Photosynthesis also turns light energy into chemical energy, which provides food for us. Find out the important role plants have as producers in food chains . Photosynthesis is important for all life on earth!

Learn more about how photosynthesis is an important part of the carbon cycle.

Free printable photosynthesis worksheet!

Photosynthesis Activity

• Photosynthesis Worksheet
• Blank paper

Instructions:

STEP 1: Print out the photosynthesis worksheet and color it in.

STEP 2: Cut out the pieces of the diagram.

STEP 3: Glue the pieces in the appropriate place on another piece of paper to display the photosynthesis process.

Learn About Plant Cells

If you want to continue your exploration of plants and biology on a more in-depth level, look at this plant cell STEAM project . We also have a similar animal cell STEAM activity and a printable project pack for both !

More Plant Activities For Kids

Looking for more plant lesson plans? Here are few suggestions for fun plant activities that would be perfect for elementary to middle school students.

• Grab some leaves and find out how plants breath .
• Set up a flower dissection lab !
• Learn about how water moves through the veins in a leaf.
• Explore the carbon cycle and the nitrogen cycle .
• See up close how a seed grows with a seed germination jar.
• Learn about osmosis when you try this fun potato osmosis experiment with the kids.

Printable Spring Pack

If you’re looking to grab all of the printables in one convenient place plus exclusives with a spring theme, our 300+ page Spring STEM Project Pack is what you need!

Weather, geology, plants, life cycles, and more!

Subscribe to receive a free 5-Day STEM Challenge Guide

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Photosynthesis for Kids: Lesson and Printables

Plants are unique organisms because they are one of only three life forms able to produce their own food. The only other organisms capable of this are algae and some bacteria. This unit introduces kids ages 9 to 12 to the process of photosynthesis.

Learn more about plant life with these fun printable activities !

What is photosynthesis?

Photosynthesis is the way in which plants make their own food. Plants need four things to accomplish it.

The first is sunlight . All plants on earth convert sunlight into food. Sunlight is a form of energy that the plant changes into another form of energy that the plant can use to live.

The second is water . Plants absorb water through their roots, and sometimes through their leaves. Water is not only part of the photosynthesis process, but it helps the plant to grow and stay upright!

The third thing plants need is carbon dioxide . Plants “breathe in” carbon dioxide through tiny pores in their leaves. These pores are called stomata. And they “exhale” oxygen. This is one of the reasons why plants, and especially trees, are so important to our planet. They produce the air we need to breathe and survive… and they use the “waste” air that we produce for their own survival.

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Kristian Peters — Fabelfroh / CC BY-SA

And the last thing plants need is chlorophyll . This is a pigment inside the chloroplast organelles found inside the plant’s cells. Chlorophyll is responsible for absorbing light for photosynthesis. But it also gives plants their green color because it reflects green wavelengths in white light.

How does photosynthesis work?

Plants absorb water and minerals from their roots. They also absorb carbon dioxide. These three mix together in the plant to form a substance called raw sap . The plant then uses its chlorophyll to absorb sunlight and takes the energy from the sunlight and converts it into a different type of stored energy.

Plants then take this stored energy and use it to turn the raw sap into glucose, a type of sugar. This new sugar is called elaborated sap . It flows through the plant and provides food for the cells so that the plant can grow and reproduce. Sometimes plants store any extra elaborated sap in their roots and fruits, which is what makes sweet potatoes and strawberries so yummy!

Why is photosynthesis important?

Photosynthesis is critical to life on this planet for two reasons. The first reason is that plants are producers. This means that they produce their own food using sunlight. And producers are at the bottom of the food chain.

All other life forms are either consumers or decomposers. Consumers may eat producers (such as rabbits) or other consumers (such as eagles) or both (such as bears). Decomposers break down dead plants or animals. Earthworms and fungi are examples of decomposers.

Either way, all life is dependent on plants. And plants can only exist thanks to photosynthesis.

The second reason is that during the process of photosynthesis, plants clean our air by absorbing carbon dioxide and producing oxygen. They help sustain our planet and make it possible for most life forms to exist.

©Arthur Gamsa

Activities for learning about photosynthesis for kids

Here are some of our printable resources for helping your child learn more about photosynthesis.

Science Activity #1: As mentioned, one of the reasons that photosynthesis is so important to all life on earth, is that it is found at the bottom of all food chains and food webs. Producers rely on photosynthesis to create their own food. Print our Food Chain activity sheet and cut out the life forms. Then choose a few to create your own food chain. Be sure to label the producers, consumers, and decomposers!

Simple Food Chain Photosynthesis Lesson Worksheet

Activity #2: We’ve described the process that a plant goes through to produce its own food. Print our Photosynthesis Process worksheet and label the steps that take place during photosynthesis.

Activity #3: Be a scientist and explore photosynthesis with an experiment. Download our Photosynthesis Experiment pages and follow the directions. Use whatever materials you can find at home.

Inspired to get more hands-on learning with plants? Turn this unit into a bigger lesson with this guide to starting a garden at your school !

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Monica Olivera is a homeschooling mother of two and a freelance education writer. Her site, Mommy Maestra, helps Hispanic parents get more involved in their children's education by providing resources, tips, and opportunities.

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