Unit 6 · Ecosystems & Our Footprint · Week 1
Where does the energy in a schoolyard come from?
A patch of schoolyard grass teems with insects, spiders, birds, and hidden fungi — dozens of living things packed into a few square metres. Every single one of them needs energy to survive. Where does all that energy come from?
Start here
How we work this lesson (our expectations)
- Follow the energy — ask "where did it come from?" at every step
- Build models together — a diagram we draw together is better than one we copy
- Respectful disagreement is part of science — challenge ideas, not people
- Supports are for everyone — open any you want, any time
30-second check-in self-management
Before we start, take one slow breath and notice your energy level right now. Scale of 1 (running on empty) to 5 (ready to go). If you are at a 1 or 2, that is fine — this lesson starts outside (in your imagination) and builds slowly. You can listen to any section aloud with the Listen button.
Do-Now Quick recall
Pull from what you already know — no looking back. Three questions from earlier this year.
- Unit 1 spiral Energy is never created or destroyed — only transferred. Name one example from Unit 1 where energy moved from one object to another.
- Unit 5 spiral Plants make their own food through photosynthesis. What raw materials do they need, and what do they produce?
- Name any living thing you have seen in a schoolyard or park. What do you think it eats — and what eats it?
The phenomenon
Stand at the edge of a patch of grass on a sunny school day. Look closely. You might spot a caterpillar chewing a leaf, a spider waiting in a web, or a sparrow watching for its next meal. This patch is alive in every direction — and every organism is spending energy just to exist: moving, digesting, growing. Where does all that energy come from? Trace the arrows in the diagram above. Every chain leads to the same source: the sun. Grass captures sunlight through photosynthesis. A caterpillar eats the grass. A spider eats the caterpillar. A bird eats the spider. Energy flows along a single path — but notice something: at every step, some energy is lost as heat to the surroundings. Not wasted, but transferred away — and that is why the amounts get smaller and smaller as you move up the chain. Our question: how does the sun's energy reach every living thing in that patch?
A patch of grass on a sunny day is packed with living things — insects, spiders, birds. Every one of them needs energy. Look at the diagram: every arrow leads back to one source: the sun. Grass uses sunlight to make food. A caterpillar eats the grass. A spider eats the caterpillar. A bird eats the spider. Energy moves along that path — but at every step, some is lost as heat. That's why there's less energy the higher you go. How does the sun's energy get to everything in that patch?
Notice & Wonder. Write one thing you notice about where the energy comes from and one thing you wonder about what happens to it along the way.
Build it From food chains to energy pyramids
Three connected ideas, one step at a time. After each step there is a quick check before we move on.
Step 1 — Producers capture the sun's energy
Every ecosystem needs an energy source, and for almost every ecosystem on Earth that source is the sun. Producers — mostly plants and algae — capture sunlight and use it in photosynthesis to build sugar (food) from carbon dioxide and water. That stored chemical energy then becomes available to every other organism. Without producers there is no energy entering the food web at all. This is your spiral connection: from Unit 5, you know that photosynthesis captures light energy and stores it in sugar molecules. Those same molecules are what the caterpillar is eating off the leaf.
Producers (plants, algae) catch sunlight and turn it into food using photosynthesis. Every other living thing gets energy by eating producers or eating something that ate a producer. No producers = no energy in the ecosystem. (You learned photosynthesis in Unit 5 — now you see where that food goes next.)
Step 2 — Consumers transfer energy up the food web
Consumers get their energy by eating. A primary consumer eats producers directly (the caterpillar eats grass). A secondary consumer eats the primary consumer (the spider eats the caterpillar). A tertiary consumer eats the secondary consumer (the bird eats the spider). Together these feeding relationships form a food chain. When multiple chains overlap — because one organism has many food sources — we get a food web. The direction of energy flow is always the same: from producers upward through consumers. And at every transfer, some energy is converted to heat and lost to the surroundings. This is your Unit 1 spiral: energy is never destroyed; it is transferred, and every transfer is imperfect — some becomes heat.
Consumers eat to get energy. The caterpillar eats grass (primary consumer). The spider eats the caterpillar (secondary consumer). The bird eats the spider (tertiary consumer). These feeding links make a food chain. When chains connect, they make a food web. Energy always moves from producers up to consumers. At every step, some energy becomes heat and leaves the system.
Step 3 — The energy pyramid: why there are fewer top predators
Because energy is lost as heat at every step, the total amount of energy available gets smaller as you move up the food chain. Scientists show this with an energy pyramid: a wide base (lots of energy in producers), a narrower middle (less energy in primary consumers), a narrower top (even less in secondary consumers), and a very narrow peak (very little in top predators). On average, only about 10% of the energy at one level is transferred to the next; 90% is lost as heat. That is why a schoolyard can support many blades of grass, far fewer caterpillars, fewer spiders, and very few birds. This explains a pattern you might have noticed: there are always many more prey animals than predators in any ecosystem.
Each level of the food chain has less energy than the one below it because energy is lost as heat at each step. About 90% is lost each time — only 10% passes up. This is shown as an energy pyramid: wide at the bottom (lots of energy in plants), narrow at the top (very little in top predators). That is why there are always more prey than predators.
Worked example — modeling energy flow in the schoolyard patch (watch how an expert reasons)
Starting point: the sun delivers 10,000 units of light energy to the grass in a patch. The grass captures about 1,000 units in photosynthesis; the rest is reflected or converted to heat.
Step up to caterpillars: caterpillars eat the grass and get about 100 units (10% of 1,000); the other 900 units were used by the grass for its own life processes or lost as heat.
Step up to spiders: spiders eat the caterpillars and get about 10 units (10% of 100).
Step up to birds: birds eat the spiders and get about 1 unit (10% of 10).
At every step, energy is transferred — never created. And at every step, most of it leaves as heat. This is why the pyramid is narrow at the top: top predators have access to very little of the original solar energy.
Show me the energy pyramid as a diagram Tier 2 · visual
Draw four stacked bars, widest at the bottom:
Level 4 (top predator — bird): 1 unit of energy | very narrow
Level 3 (secondary consumer — spider): 10 units | narrow
Level 2 (primary consumer — caterpillar): 100 units | medium
Level 1 (producer — grass): 1,000 units | widest
Label the arrow between each level: "90% lost as heat" going sideways, "10% passes up" going up.
Your turn Model the energy flow
Build a food web and explain the energy pattern. Choose how you respond — all are equally valid.
The task: Think about a schoolyard or outdoor space near you. Pick at least four organisms (one producer, at least two consumers, and one decomposer or top predator). Draw or describe the food web, and explain: (1) where the energy enters the web; (2) what happens to energy at each step; and (3) why there are fewer top predators than producers.
I want sentence starters and a graphic organizer Tier 2 · frames
The energy in my food web comes from ________, because ________.
When the [producer] is eaten by the [primary consumer], energy ________ from one organism to the next. At each step, ________% of the energy is lost as ________.
There are fewer top predators because ________.
Word bank: sun · photosynthesis · producer · consumer · energy · heat · food web · food chain · energy pyramid · transfer · 10% · 90%
Let's make it concrete first Tier 3 · re-teach
Analogy: Imagine passing a $100 bill through a crowd. Each person takes $90 for the "cost" of passing it along, and hands on only $10. By the time it reaches the fifth person, there's almost nothing left. The original $100 is the sun's energy. Each person keeping $90 is the heat lost at that level. The amount that reaches the "top" (last person) is tiny. That's exactly how energy shrinks from the bottom to the top of the food chain.
Fill in: The sun's energy is like the ____. Each organism in the food chain keeps most of it as ____, and passes on only ____%. That's why there is less energy at the ____ of the pyramid.
Now draw a simple three-level chain: Sun → [a plant] → [an insect] → [a bird]. Label the arrows "energy transferred" and draw a sideways arrow at each step saying "heat lost."
Push my thinking Extension
Most ecosystems lose about 90% of energy at each trophic level, but some are more efficient. Research the "trophic efficiency" of a real ecosystem you find interesting. How does that efficiency change the shape of its energy pyramid? Then design a thought experiment: if the trophic efficiency were 50% instead of 10%, how would the schoolyard ecosystem change? Would there be more or fewer top predators? How would the food web look different?
Check yourself Did it click?
- explain that producers capture the sun's energy and it flows through consumers;
- describe why energy decreases at each level of a food chain (heat loss);
- use an energy pyramid to explain why top predators are rare.
A student says: "The top predator in a food web has the MOST energy because it is the most powerful." What is wrong with this reasoning?
Re-teach: energy flows one way and shrinks at every step Tier 3
Two common mix-ups: (1) thinking energy cycles like matter, and (2) thinking the top of the food chain has "the most" energy. Here is the key model: Energy flows in ONE direction — from sun → producers → consumers — and at each step, about 90% is converted to heat. It does not cycle back. The energy pyramid shows this clearly: the bottom (producers) holds the most energy; each level above holds less and less. Top predators are powerful, but they have access to the least energy of all — which is exactly why there are so few of them. Re-read option B and look at the energy pyramid diagram in the Tier-2 support above.
Reflect, then show what you know
Reflection metacognition + SEL
What part of today's model surprised you most — and does it change how you think about eating or being eaten? There is no wrong answer. Connecting science to your own experience is part of what scientists do too.
Exit ticket — answer on paper or in your notebook. (2 new · 2 spiral · 1 transfer)
- New In your own words, explain why there can only be a few top predators in any ecosystem. Use the phrase "energy pyramid."
- New A grassland has grass, rabbits, foxes, and hawks. Draw the food chain and label the producer, primary consumer, secondary consumer, and tertiary consumer.
- Spiral — Unit 1 Energy is never created or destroyed (Unit 1). So where does the "lost" heat energy from each step in the food chain actually go?
- Spiral — Unit 5 Photosynthesis stores energy in sugar (Unit 5). How does that stored energy eventually reach a top predator like a hawk?
- Transfer → W2 A caterpillar dies on the ground and a mushroom grows on its remains. Where is the matter (the atoms that made the caterpillar) going — and is energy flowing in the same direction?
Educator panel — facilitation, accommodations, answer key
At a glance
Standard: 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. 3D: SEP Developing & Using Models · DCI LS2.B Cycle of Matter and Energy Transfer in Ecosystems · CCC Energy & Matter. Throughline: launches the year-capstone unit by connecting Unit 5 photosynthesis (energy enters the web) and Unit 1 energy transfer (energy is never created; "lost" heat is a real transfer). Students will extend this model in W2 (matter cycling), W3 (web changes), and W4 (human impact).
Materials (optional, fully digital-capable): a small outdoor observation window (schoolyard patch visit for 5 min), or the embedded SVG scenario; student notebook. No lab materials required.
Facilitation arc (Rosenshine)
- Launch the Do-Now while you take attendance (3 min) — items 1 and 2 activate the two key spirals; item 3 surfaces prior knowledge about local organisms.
- Reveal the phenomenon SVG; cold-call 2–3 students to share a notice/wonder; write wonders on the board (3 min).
- Build Steps 1–3 with the class; pause after Step 2 to ask: "Can you name a Unit 1 idea hiding in this food chain?" (12 min).
- Differentiated practice — students choose their response mode; circulate and look for who draws the energy arrows in reverse or who says "energy cycles" (redirect to the re-teach panel) (15 min).
- Self-check — quick poll (A/B/C); route any A/C students to #reteach-energyflow (5 min).
- Brain break (2 min), reflection + exit ticket (10 min).
IEP / 504 accommodation cards
Common accommodations mapped to this lesson
| Accommodation | How it's already built in / what to do |
|---|---|
| Text read aloud | Every passage has a Listen button (TTS); simplified toggle shortens it. |
| Reduced reading load | "Reading: Simplified" swaps in shorter plain-language text throughout. |
| Chunking / extended time | Build section has three clearly numbered steps; progress saves automatically. |
| Sentence frames / word bank | Tier-2 panel provides frames and a 12-word bank for the CER task. |
| Concrete analogy / reduced load | Tier-3 provides the "$100 bill passed through a crowd" analogy and a guided cloze. |
| Alternative response mode | Draw, write, or record — all accepted equally. |
| Behavior / focus (504, ADHD) | Named expectations, 30-sec check-in, physical energy-pyramid brain break. |
| Multilingual / EL | Simplified text, SVG diagram with labels, word bank in Tier-2, home-language reflection allowed. |
Exit ticket answer key
- Top predators have access to very little energy because about 90% is lost as heat at each level of the energy pyramid. By the time energy reaches the top, so little remains that the ecosystem can only support a small number of top predators.
- Grass (producer) → Rabbit (primary consumer) → Fox (secondary consumer) → Hawk (tertiary consumer). Arrows should point upward in the chain: grass to rabbit, rabbit to fox, fox to hawk.
- The "lost" heat energy transfers to the surrounding air and soil — warming the environment very slightly. It does not disappear; it spreads out and is no longer available to do useful work in the food chain. (Unit 1: energy is transferred, not destroyed.)
- Through photosynthesis, the grass stored the sun's energy in sugar. When the caterpillar eats the grass it gets some of that energy. When the spider eats the caterpillar, it gets some of what the caterpillar had. Each step passes energy upward until the hawk gets a tiny fraction of what started with the sun.
- (Transfer preview for W2.) The matter (atoms) in the caterpillar is broken down by the mushroom (a decomposer) and returned to the soil as nutrients. The atoms are recycled — they are not destroyed. However, the energy is NOT flowing the same way matter cycles: the energy that was in the caterpillar is released as heat during decomposition and leaves the food web, while the matter (the atoms) stays in the ecosystem and is reused.
Why it's designed this way
The schoolyard patch is the anchor phenomenon for the whole unit — it grounds every abstract concept in a place students can observe. The Do-Now explicitly spirals Unit 1 (energy transfer) and Unit 5 (photosynthesis) before students encounter the food web, activating prior knowledge that the new lesson will extend rather than replace (cognitive load management, Sweller 1988). The energy-pyramid brain break uses embodied cognition to encode the abstract "levels of energy" concept physically. The transfer item in the exit ticket (item 5) deliberately previews Week 2's matter-cycling concept by raising the exact question that decomposers answer — creating a "desirable difficulty" that primes long-term retention (Bjork, 1994). The misconception re-teach panel addresses the two most common confusions in this topic: (a) energy cycles like matter, and (b) top predators have the most energy. Both misconceptions have been documented in the science education research (Driver et al., 1994) and are specifically addressed in the NGSS progressions for MS-LS2.