Science (EVS K-5) · Class 3 · Nature's Variety: Plants and Animals · Term 1

How Plants Make Their Food

Exploring the process of photosynthesis, how plants make their own food, and its importance for all life.

• CBSE Learning Outcomes
• NCERT: Class 7, Chapter 1: Nutrition in Plants

About This Topic

Photosynthesis is the process by which plants make their own food, using sunlight, water, and carbon dioxide. Class 3 students learn that green leaves contain chlorophyll, which captures sunlight to turn these into glucose for the plant's energy and oxygen for living things. They explore key questions: plants need these three essentials, leaves face sunlight and appear green due to chlorophyll, and a plant in a dark cupboard wilts without food production.

In the CBSE EVS curriculum, this fits the Term 1 unit Nature's Variety: Plants and Animals, drawing from NCERT Class 7 Nutrition in Plants basics adapted for young learners. It connects plant health to daily observations like sunny gardens thriving, building awareness of plants as food producers at the base of food chains.

Active learning benefits this topic greatly since photosynthesis involves unseen chemical changes. Hands-on tests, such as comparing plants in light and dark or observing leaf colour changes, provide concrete evidence. Collaborative predictions and recordings help students refine ideas through discussion, making the process real and memorable.

Key Questions

1. What three things does a plant need to make its own food?
2. Why do you think most leaves are green and grow facing the sunlight?
3. What do you think would happen to a plant kept inside a dark cupboard for a week?

Learning Objectives

• Identify the three essential components plants require for photosynthesis: sunlight, water, and carbon dioxide.
• Explain the role of chlorophyll in capturing sunlight for food production in plants.
• Compare the outcomes for a plant exposed to sunlight versus one kept in darkness for a week.
• Illustrate the basic process of photosynthesis using a simple diagram.

Before You Start

Parts of a Plant

Why: Students need to be familiar with the basic parts of a plant, such as leaves, stem, and roots, to understand where photosynthesis occurs and how materials are transported.

What Living Things Need

Why: Prior knowledge about the basic needs of living things (food, water, air) helps students connect the concept of plants making their own food to the broader idea of survival.

Key Vocabulary

Photosynthesis	The process where green plants use sunlight, water, and carbon dioxide to create their own food (sugar) and release oxygen.
Chlorophyll	The green pigment found in plant leaves that absorbs energy from sunlight, which is essential for photosynthesis.
Carbon Dioxide	A gas present in the air that plants take in through their leaves to make food during photosynthesis.
Oxygen	A gas that plants release into the air as a byproduct of photosynthesis, which is necessary for animals and humans to breathe.

Watch Out for These Misconceptions

Common Misconception

Plants eat soil to make food.

What to Teach Instead

Plants absorb water and minerals from soil but make food using sunlight, air, and water. Experiments with hydroponic setups or potted plants without soil show growth, and group discussions clarify the role of roots versus leaves.

Common Misconception

Plants do not need sunlight.

What to Teach Instead

Without sunlight, plants cannot produce food and wilt, as seen in dark cupboard tests. Active observations over days help students track changes and connect lack of light to no photosynthesis.

Common Misconception

Leaves are green from paint or dirt.

What to Teach Instead

Green colour comes from chlorophyll inside cells for light absorption. Extracting chlorophyll through boiling demos lets students see the pigment, correcting ideas via direct evidence and peer sharing.

Active Learning Ideas

Experiment: Light and Dark Plants

Select two similar potted plants. Place one in sunlight and the other in a dark cupboard for five days. Have students observe and record daily changes in leaf colour and plant health, then compare results in groups.

45 min·Small Groups

Demonstration: Chlorophyll Extraction

Boil spinach leaves in water, then in alcohol over a hot plate. Students watch the green colour move to the alcohol and test it with iodine for starch. Discuss how chlorophyll helps make food.

30 min·Whole Class

Model: Photosynthesis Jar

Fill a clear jar with water, add a plant sprig and baking soda for carbon dioxide. Seal and place in sun. Students note bubbles of oxygen after 30 minutes and draw the process.

40 min·Pairs

Stations Rotation: Plant Needs

Set up stations for sunlight (torch on leaf models), water (wilting celery), air (balloon with plant). Groups rotate, predict outcomes, and test simple setups, recording evidence.

50 min·Small Groups

Real-World Connections

• Farmers and gardeners observe which plants grow best in sunny locations, understanding that sunlight is crucial for their growth and food production. This helps them decide where to plant specific crops for optimal yield.
• Forest rangers and conservationists monitor the health of trees in national parks. They understand that healthy, green leaves, rich in chlorophyll, indicate that the forest is effectively performing photosynthesis, supporting the entire ecosystem.
• Food scientists and nutritionists study the energy stored in plants. They know that the sugars produced through photosynthesis are the primary source of energy in fruits, vegetables, and grains that humans and animals consume.

Assessment Ideas

Quick Check

Show students pictures of different plant parts (leaf, root, flower) and ask them to point to the part where photosynthesis primarily happens. Follow up by asking why that part is best suited for the job.

Exit Ticket

Give each student a small card. Ask them to write down two things a plant needs to make food and one thing it produces. Collect these as they leave the classroom.

Discussion Prompt

Pose the question: 'Imagine you have a plant that is not getting enough sunlight. What might happen to its leaves, and why?' Facilitate a class discussion, encouraging students to use the vocabulary learned.

Frequently Asked Questions

What three things does a plant need to make its own food?

Plants need sunlight, water from the soil, and carbon dioxide from the air. Chlorophyll in green leaves uses sunlight to combine these into glucose and oxygen. Simple classroom tests confirm each need's role in keeping plants healthy.

Why do most leaves grow facing the sunlight and appear green?

Leaves face sunlight to capture maximum energy for photosynthesis. They appear green because chlorophyll absorbs red and blue light but reflects green. Variegated leaf observations show white parts lacking chlorophyll cannot make food well.

What happens to a plant kept in a dark cupboard for a week?

The plant wilts, leaves turn yellow, and growth stops because it cannot photosynthesise without light. It uses stored food until exhausted. Long-term experiments demonstrate this, linking to real garden care.

How can active learning help Class 3 students understand photosynthesis?

Active learning engages students through experiments like light-dark plant comparisons or chlorophyll extraction, turning abstract ideas into visible results. Group rotations and predictions build skills in observation and teamwork. Discussions refine misconceptions, making concepts stick better than rote learning, as students connect school activities to home plants.