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Photosynthesis: How Plants Turn Sunlight Into Food

A single-period, 5E inquiry lesson where students discover that a plant's mass comes mostly from the air — then model how light energy becomes the chemical energy that powers nearly every food web on Earth.

Grades 6–8Middle School 50 minutes1 class period 5E ModelInquiry-based 6 StandardsNGSS + CCSS
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Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Identify the reactants (carbon dioxide, water, light) and products (glucose, oxygen) of photosynthesis.
  • ✓Explain how photosynthesis transforms light energy into chemical energy stored in glucose.
  • ✓Build a model showing the flow of matter and energy into and out of a plant.
  • ✓Use evidence to explain photosynthesis's role in food webs and the carbon cycle.
Essential Question

Where does a giant tree's mass actually come from — the soil beneath it, or the air around it?

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5E Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Tasks
Explore · Interactive Model

The Photosynthesis Machine

Project this for the whole class or let groups drive it. Slide the sunlight up and down, flip between day and night, and have students record what happens to the sugar and oxygen output in their science notebooks.

🌿 Live Model — adjust the light, watch the reaction Try it
chloroplast CO₂ CO₂ H₂O H₂O O₂ O₂
Sunlight intensity 70%
🍬 Glucose produced—
💨 Oxygen released—
Notice: as light increases, output rises — but then levels off. Ask students: what else might the plant run out of? (CO₂, water, temperature — the limiting factors.)
The Lesson · 5E Model

Fifty minutes, five moves

Tap any phase to open the teacher moves and student actions. The timing bar on the left adds up to one class period.

1

Engage — The Impossible Tree

5 min

A 400-year-old oak weighs many tons. Where did all that stuff come from?

👩‍🏫 Teacher Moves

  • Pose the hook: "A tiny acorn becomes a 20-ton oak. Where did the mass come from?"
  • Run a quick 4-corners poll: Soil · Water · Air · Sunlight.
  • Share van Helmont's willow experiment — the soil barely lost weight. Let the surprise land.

🎒 Student Actions

  • Commit to a corner and defend it in one sentence.
  • Record their prediction in their notebook to revisit at the end.
  • Surface the tension: "How can something grow… out of air?"
2

Explore — Drive the Machine

12 min

Students manipulate the interactive model above and collect evidence — no formula given yet.

👩‍🏫 Teacher Moves

  • Send groups to the Photosynthesis Machine (or run a live Elodea/leaf-disk demo).
  • Ask them to test: "What goes in? What comes out? What happens at night?"
  • Circulate; resist naming the parts — let them describe what they see.

🎒 Student Actions

  • Slide light from 0→100% and log the effect on sugar & oxygen.
  • Flip to night mode and record: the reaction stops.
  • Sketch the inputs/outputs as arrows — their first model.
3

Explain — Name the Reaction

13 min

Formalize the vocabulary and the equation — then have students build it themselves.

👩‍🏫 Teacher Moves

  • Introduce chloroplast, chlorophyll, reactant, product, glucose.
  • Reveal the equation and connect each term back to the model they explored.
  • Drive home the big idea: mass comes from CO₂ in the air; energy comes from light.

🎒 Student Actions

  • Use the builder below to assemble the balanced equation.
  • Label their Explore sketch with the correct scientific terms.
  • Turn-and-talk: "Which arrow is matter? Which is energy?"
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4

Elaborate — Zoom Out to the Food Web

12 min

Connect one leaf's chemistry to ecosystems, energy flow, and the carbon cycle.

👩‍🏫 Teacher Moves

  • Trace the glucose: growth, storage, and fuel for cellular respiration.
  • Show that nearly every food web starts with a producer doing this.
  • Bridge to climate: photosynthesis pulls CO₂ out of the atmosphere.

🎒 Student Actions

  • Predict: rainforest vs. desert — where is more photosynthesis happening, and why?
  • Explain what happens to the plant's food at night.
  • Add producers → consumers arrows to extend their model.
5

Evaluate — Exit Ticket

8 min

Three quick checks for understanding — students answer before they revisit their opening prediction.

👩‍🏫 Teacher Moves

  • Hand out the exit ticket (previewed below) or run it on-screen.
  • Have students compare their answer to the Engage prediction.
  • Collect as formative data to plan tomorrow.

🎒 Student Actions

  • Name the reactants and products from memory.
  • Answer the essential question with evidence.
  • Model one arrow of matter and one of energy.
Standards Alignment

Built to the standards you report on

Aligned to Next Generation Science Standards and Common Core literacy in science. State-standard crosswalks available on request.

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-LS1-7

Develop a model to describe how food is rearranged through chemical reactions, forming new molecules that support growth and release energy.

CCSS
RST.6-8.7

Integrate quantitative or technical information expressed in words with a version expressed visually (a diagram or model).

CCSS
WHST.6-8.2

Write an informative/explanatory text to examine a topic and convey ideas through relevant, well-organized evidence.

SEP
Practice

Developing & Using Models · Constructing Explanations from evidence.

CCC
Crosscutting

Energy & Matter — tracking flows, cycles, and conservation through a system.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Picture vocabulary cards for each term with the equation labeled visually.
  • Sentence frames: "The reactants are ___. The products are ___."
  • Pair with a peer to narrate the model aloud before writing.

Support & Access

IEP / 504
  • Word version of the equation instead of chemical formulas.
  • Provide a partially-completed model to finish, not build from scratch.
  • Extended time; chunk the exit ticket to one question at a time.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Research how C4 and CAM plants survive with less water.
  • Design an experiment isolating one limiting factor (light color, CO₂).
  • Move on to the 2-day leaf-disk lab below.
Materials

What to gather

  • 📽️Projector / board
  • 📓Student science notebooks
  • 💻This interactive model
  • 🌱Small plant or leaf per group (optional)
  • ✏️Colored pencils
  • 🎫Exit-ticket slips
Vocabulary

Ten key terms — hover for a quick definition

photosynthesismaking food from light chloroplastthe structure where it happens chlorophyllgreen pigment that traps light glucosethe sugar produced reactantan ingredient going in productwhat comes out carbon dioxideCO₂ from the air chemical energyenergy stored in glucose light energyenergy from the sun stomataleaf pores for gas exchange
Evaluate

Exit Ticket

Preview the three formative checks. Tap "Sample answer" to see what mastery looks like — hide them before you print for students.

QUESTION 1
List the three reactants and two products of photosynthesis.
Reactants: carbon dioxide (CO₂), water (H₂O), and light energy. Products: glucose (C₆H₁₂O₆) and oxygen (O₂).
QUESTION 2
A tree gains tons of mass as it grows. Using evidence, where does most of that mass come from?
Most of the mass comes from carbon dioxide in the air. The carbon in CO₂ is built into glucose during photosynthesis and then into the plant's tissues — not from the soil, as van Helmont's experiment showed.
QUESTION 3
In your model, draw one arrow that shows matter moving and one that shows energy moving.
Matter arrow: CO₂ and H₂O entering (or O₂ leaving). Energy arrow: light energy entering from the sun, transformed into chemical energy stored in glucose.

Going deeper? Turn it into a 2-day investigation.

Add the classic leaf-disk float lab: students sink spinach disks in baking-soda solution, then time how fast they rise under different light conditions to measure the rate of photosynthesis and identify limiting factors. Full lab handout available in the Science library.

Study · Flashcards

Study the key terms

Tap a card to flip it, then rate whether you knew it. Built from this lesson’s vocabulary.

🃏 Photosynthesis: How Plants Turn Sunlight Into FoodFlip
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Practice · Quiz

Check your understanding

A quick self-check with instant feedback, drawn from this lesson’s key terms.

📝 Photosynthesis: How Plants Turn Sunlight Into FoodQuiz
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Practice · Worksheet

Printable worksheet

A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.

🖨️ Photosynthesis: How Plants Turn Sunlight Into FoodPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: carbon dioxide, chemical energy, chlorophyll, chloroplast, glucose, light energy, photosynthesis, product, reactant, stomata
  1. CO₂ from the air
  2. leaf pores for gas exchange
  3. green pigment that traps light
  4. the structure where it happens
  5. the sugar produced
  6. an ingredient going in
  7. making food from light
  8. energy from the sun
  9. energy stored in glucose
  10. what comes out
Answer key — Part A: 1) carbon dioxide · 2) stomata · 3) chlorophyll · 4) chloroplast · 5) glucose · 6) reactant · 7) photosynthesis · 8) light energy · 9) chemical energy · 10) product