Lesson Plan How Does a Plant Make Its Own Food? Grade 7 · Ages 12–13 Life Science 45 minutes Inquiry-based "If plants can't hunt or shop for food — how do they stay alive, grow, and feed nearly every living thing on Earth?" 🎯 Learning objectives RecallIdentify the reactants (water, carbon dioxide, sunlight) and products (glucose, oxygen) of photosynthesis. ExplainDescribe how chloroplasts capture light energy and convert it into chemical energy stored in glucose. AnalyzeCompare a plant's energy-making process with how animals obtain energy, identifying key similarities and differences. ConstructWrite a word equation and annotated diagram for photosynthesis using correct scientific vocabulary. EvaluatePredict what would happen to a plant — and to ecosystems — if one reactant (e.g., light or CO₂) were removed. 📋 Standards alignment NGSS MS-LS1-6 Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms. NGSS MS-LS2-3 Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem. CCSS.ELA-Literacy.RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks — applied here to annotating scientific diagrams and constructing word equations. 📦 Materials & preparation Student materials Printed or projected "Leaf Close-Up" worksheet (one per student) Pencil or pen Colored pencils (optional, for diagram annotation) Sticky notes (2 per student) Teacher materials Projector or whiteboard Printed or projected driving question poster Printed "Leaf Close-Up" worksheets (class set) Timer (phone or classroom clock) Teacher prep steps Print or project the "Leaf Close-Up" blank diagram worksheet Write driving question on board or prepare slide Prepare 5–6 "think-pair-share" scenario cards on board Pre-write the word-equation template on the board: ___ + ___ + ___ → ___ + ___ Prep time & notes Estimated prep time: ~15 minutes No lab equipment needed — all activities use pencil, paper, and discussion All materials are classroom-standard; no specialist supplies required ⏱ Lesson sequence · 45 minutes 1 Hook / Engage 0 – 7 min Display the driving question on the board: "If plants can't hunt or shop for food — how do they stay alive, grow, and feed nearly every living thing on Earth?" Show students a leaf (or a projected close-up image). Ask them to write silently on a sticky note: "Where do you think the mass of a tree comes from?" Most will say "soil" — this is the expected misconception. Teacher prompt "Think about a tiny acorn that becomes a massive oak tree. That tree weighs tons. Did all that mass come from the ground under it? The soil barely changes. So where did all that material come from?" (Pause. Accept all answers without correction yet.) Briefly share the historical experiment: Jan Baptist van Helmont planted a willow sapling in a pot of weighed soil. Five years later the tree weighed over 160 lbs — but the soil lost barely 2 oz. Ask: "What does that tell us?" Tell students: by the end of class, they will be able to answer exactly where a plant's mass comes from — and why that answer is one of the most important ideas in all of biology. 2 Explore — Part A: Build the equation 7 – 20 min Distribute the "Leaf Close-Up" worksheet (blank diagram of a leaf cross-section with labeled arrows pointing inward and outward). Students work in pairs to brainstorm and label: What goes into the leaf? What comes out? Guiding questions "Think about what a plant needs to survive. What does it absorb from the air? From the ground? What does sunlight do? What do we know leaves release into the air?" Allow 4 minutes of pair discussion before whole-class share-out. Draw out responses and record on the board. Guide students toward: carbon dioxide (in via stomata), water (up via roots/stem), light energy (absorbed by chlorophyll) → glucose (stored), oxygen (released). Introduce the word equation template on the board. Students fill it in on their worksheet: Word equation Carbon dioxide + Water + Light energy → Glucose + Oxygen Check understanding quickly: "Turn to your partner — which of these are inputs the plant collects from its environment? Which are outputs it creates?" 3 Explore — Part B: Annotated diagram & scenarios 20 – 33 min Students annotate their leaf diagram individually: label where each input enters, mark the chloroplast as the "factory," and draw arrows showing where outputs go. Students add 2-sentence captions explaining the role of chlorophyll and glucose. Teacher prompt during work time "Think of the chloroplast as a tiny solar panel crossed with a kitchen — it captures energy from light and uses it to cook up glucose from simple ingredients. Where on the leaf does this happen? Can you label that?" After 6 minutes, introduce 3 "What if?" scenario cards (displayed on board). Students pick one and write a 2-sentence prediction on the back of their worksheet: Scenarios A) A plant is kept in a closet with no light for 2 weeks. What happens and why? B) A factory pumps out so much CO₂ that air levels double. How might nearby plants respond? C) A drought cuts off a plant's water supply completely. What effect does this have on photosynthesis? Quick pair-share: partners compare predictions, then two or three pairs share with the class. Teacher clarifies and reinforces the word equation in context of each scenario. 4 Explain / Debrief 33 – 41 min Revisit the driving question and the sticky notes from the Hook. Ask students: "Now that you know about photosynthesis — where does most of a tree's mass actually come from?" Elicit the key insight: from CO₂ in the air, not the soil. Carbon atoms from the air become the carbon-based molecules of the plant. Run three whole-class discussion questions: 1Photosynthesis produces oxygen as a by-product. How does that connect to what animals — including us — need to breathe? What would happen to animal life if all plants suddenly stopped photosynthesising? 2Plants make glucose for energy. Animals eat to get energy. In what ways are these two strategies similar, and in what ways are they fundamentally different? 3We talk about climate change and "too much CO₂ in the atmosphere." Given what you now know, could plants help solve this problem? What are the limits of that solution? Teacher consolidates by drawing a simple energy-flow arrow on the board: Sun → Plant (glucose) → Animal/Ecosystem, reinforcing that photosynthesis is the foundation of most food chains. 5 Evaluate / Exit task 41 – 45 min Exit ticket (individual, ~3 min) On the back of the worksheet (or a fresh sticky note), students complete all three prompts before leaving: 1. Complete the word equation: ___ + ___ + ___ → ___ + ___ 2. In one sentence, explain what chlorophyll does. 3. A student says "plants get their food from the soil." Write one sentence that politely corrects this misconception using evidence from today's lesson. 🔀 Differentiation strategies Support — struggling learners Provide a partially completed "Leaf Close-Up" worksheet with reactants already labeled; students focus on completing the outputs and writing captions only. Pair with a stronger peer during the diagram and scenario phases; supply a vocabulary card with key terms (chloroplast, glucose, stomata, chlorophyll) and simple definitions. Extension — advanced students Challenge students to represent photosynthesis as a balanced chemical equation (6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂) and explain what the subscript numbers mean. Ask extension students to write a short paragraph connecting photosynthesis to the carbon cycle — specifically how carbon moves from atmosphere → plant → consumer → atmosphere. ELL / accessibility Supply bilingual vocabulary cards with diagrams; allow students to annotate their leaf diagram in their home language first, then add English labels. Use visual anchors throughout — always point to the diagram when introducing new vocabulary. The no-lab constraint is naturally accessible: all tasks are paper-based and language-scaffoldable. 🏠 Homework / Extension task Optional take-home — "Photosynthesis Journalist" Students go outside (garden, park, window ledge) and observe any plant for 5 minutes. They then write a short paragraph (or record a 60-second voice memo) "reporting from the scene" as if they are a journalist reporting on photosynthesis in action. They must include: what inputs the plant is currently gathering, what output might be happening right now, and one question they still have about the process. No equipment needed — observation and imagination only. Optionally, they may sketch the plant and annotate it using the same diagram technique from class. 🪞 Teacher reflection prompts 1How many students correctly identified all five components of the word equation on the exit ticket — and did errors cluster around inputs, outputs, or a specific term? What does that pattern suggest about which part of the lesson needs more time or a different approach next delivery? 2During the "What if?" scenarios, how deeply were students making causal connections (e.g., "less light → less energy captured → less glucose produced → slower growth") versus giving surface-level answers ("the plant dies")? Were the scenarios pitched at the right difficulty level? 3Did the van Helmont hook genuinely provoke curiosity, or did students seem to dismiss it quickly? What alternative opener — perhaps a local or personally relevant context (food, deforestation, houseplants) — might create a stronger emotional hook for this particular class next time?