Photosynthesis: How Plants Make Their Own Food (And Ours)

Objective. Students will identify the three inputs of photosynthesis (sunlight, water, carbon dioxide) and the two outputs (glucose, oxygen), and explain why plants matter for the air we breathe.

Overview

Students learn that plants make their own food through photosynthesis, a process that uses sunlight, water, and carbon dioxide to produce glucose and oxygen. The lesson builds from a warm-up observation through guided note-taking, a live demonstration showing the plant releasing water vapor, and ends with an exit ticket connecting photosynthesis to the air students breathe.

Demonstration

Seal a plastic bag around one leaf at the start of class. By the end, students see water droplets forming — physical evidence the plant is releasing water vapor from photosynthesis. AI-generated — review

Materials: clear plastic sandwich bag, twist tie, live plant

Teacher tip: If time allows, do the demo on two plants — one in sunlight, one covered with a box. The covered plant produces less condensation. Evidence that light matters.

Lesson Steps

(5 min) Teacher: Hold up the plant. Ask: 'If I forgot to water this for a month, what would happen?' Let students picture it. Then: 'What if I put it in a closet with no light for a month — same problem, or different problem?'
Students: Respond verbally. Some will say 'it dies' for both — press them to explain WHY each one kills the plant. AI-generated — review
(10 min) Teacher: Introduce 'photosynthesis' and write the equation in plain language: sunlight + water + CO2 → glucose + oxygen. Emphasize: 'Plants make their own food. They don't go to the grocery store.'
Students: Copy the equation onto the diagram handout. Color inputs and outputs. scaffolded
(8 min) Teacher: Demonstrate: seal the plastic bag around one leaf. Explain students will check it at the end.
Students: Watch demo. Predict what they'll see. scaffolded
(12 min) Teacher: Pair students. Each pair fills a 3-column chart: INPUT | SOURCE | WHY NEEDED. Circulate.
Students: Work with partner to complete chart. scaffolded
(5 min) Teacher: Reveal the bag. Ask: 'What do you see? What does that tell us?'
Students: Observe condensation. Discuss what it proves. scaffolded
(5 min) Teacher: Distribute exit tickets. Students complete individually.
Students: Complete the exit ticket. scaffolded

Assessment (exit ticket, 5 min)

Q1. Name the three things a plant needs for photosynthesis. scaffolded
Expected: Sunlight, water, carbon dioxide.
Rubric: Full credit for all three. 2/3 for any two.
Q2. Name the two things photosynthesis produces. scaffolded
Expected: Glucose (sugar/food) and oxygen.
Q3. What did the water drops in the plastic bag prove? AI-generated — review
Expected: The plant was releasing water vapor, which means it was actively doing photosynthesis.
Rubric: Credit any answer that connects the condensation to plant activity.

Teacher Notes

5th graders often think plants 'eat' dirt or water. The key move is the sentence 'plants build their own food out of air, water, and sunlight.' Slow down at that moment. For struggling learners, keep the diagram on the board throughout. For advanced learners, ask what happens to plants at night.

Discussion Prompts

(deepen understanding) If plants make their own food, why do we fertilize them? AI-generated — review
(extend beyond lesson) Could a plant survive on Mars? AI-generated — review
(extend beyond lesson) Why are rainforests called the 'lungs of the Earth'? AI-generated — review

Vocabulary

photosynthesis scaffolded: The process plants use to make food from sunlight, water, and carbon dioxide.
Example: Every green leaf is doing photosynthesis right now.
glucose scaffolded: A type of sugar that plants make and use as food.
carbon dioxide scaffolded: A gas in the air that plants take in through their leaves.
Example: We breathe it out; plants breathe it in.

Common Misconceptions

Misconception: Plants eat dirt.
Correction: Plants absorb minerals from soil, but minerals are not food. Plants build their own food via photosynthesis.
How to address: If a student says this, ask: 'What would happen if we put a plant in nutrient-rich soil in a closet with no light?' Then walk them through why it would still die.

Differentiation

Struggling: Pair with a strong partner for the chart. Provide a word bank (sunlight, water, CO2, glucose, oxygen). Keep the diagram visible throughout the lesson.

Advanced: Ask: 'If photosynthesis needs sunlight, how does a tree survive winter when days are short?' Let them hypothesize before explaining stored glucose.

Multilingual: Provide diagram labels in student's home language where possible. The visual equation transcends language.

Accommodations for students with disabilities

Supports for IEP/504 accommodations tied to this lesson. Pair with the student’s existing plan.

Visual: Provide a tactile version of the photosynthesis diagram (raised lines or felt arrows). Enlarge the equation on the anchor chart to at least 36pt. Describe the demo bag aloud as it forms droplets for students with low vision.
Auditory: Post the three inputs and two outputs on the board in written form alongside the oral equation. If a student wears FM/hearing technology, face the student when saying the key equation words.
Motor / physical: Pre-label the diagram handout for students with fine-motor difficulty (students circle rather than write). Allow voice response on the exit ticket.
Cognitive / attention: Pre-teach the words 'photosynthesis,' 'glucose,' and 'carbon dioxide' a day before the lesson. Provide the 3-column chart partially filled in for students who need scaffolding. Break the equation into inputs-first, outputs-second.
Behavioral / emotional: Allow a fidget tool during the 12-minute partner chart work. Offer a quiet reset spot near the teacher desk if the demo's anticipation gets overwhelming.

The demo itself is low-sensory (quiet, visible over time), which helps most students. Position the plant so every student can see without crowding; crowding is the primary behavioral trigger for this lesson.