Unit 6 · Ecosystems & Our Footprint · Week 4
What is our footprint?
A habitat that was grassland thirty years ago is now a parking lot, a neighborhood, and a small remnant patch. How has that change redirected the energy and matter that used to flow through the ecosystem — and what does that mean for the living things that depended on it?
Start here
How we work this lesson (our expectations)
- Follow the energy and matter — ask "where did it go?" every time something changes
- Scale matters — trace from one person's choices to large-scale patterns in data
- Evidence comes before conclusions — read the graph before you explain it
- Supports are for everyone — open any panel you want, any time
30-second check-in self-awareness + social awareness
Take one slow breath. Think about something near your home — a field, a creek, a wooded lot — that changed in recent years. Maybe it was built on, paved over, or cleared. What was there before? Who else was living there? Rate your focus 1–5. If you are at a 1 or 2, the simplified reading and the Listen button are ready when you need them. Today's data reading is in small steps, so you can pause at any point.
Do-Now Quick recall
Three questions from Weeks 1–3. No looking back — pull from memory.
- W1 spiral About what percentage of energy is transferred from one trophic level to the next in a food chain? What happens to the rest?
- W2 spiral What is the key difference between how energy moves through an ecosystem and how matter moves through an ecosystem?
- W3 spiral In Week 3, removing one species from a food web caused a trophic cascade. List one organism that increased and one that decreased when spiders were removed from the schoolyard web.
The phenomenon
Look at the chart. In 2000, almost two-thirds of this watershed was grassland or wetland — alive with grasses, wildflowers, insects, amphibians, and birds. By 2024, more than half the land is paved, built on, or otherwise developed. The grassland and wetland are now less than a third of what they were. This is not a natural fluctuation. This is a permanent redirection of the energy and matter flows that used to run through those habitats. The photosynthesis that once captured solar energy in that grassland no longer happens there. The carbon that used to cycle through those soils and organisms is now under concrete. The food web that depended on that habitat — caterpillars, spiders, birds, frogs, and decomposers — has lost its foundation. Every bar that drops on the green side of this chart represents a trophic cascade (Week 3) that is still unfolding, and a change to how matter (Week 2) and energy (Week 1) flow through the region. Our question: how do human activities redirect energy and matter flows in ecosystems, and what are the consequences at different scales?
Look at the chart. In 2000, most of this watershed was grassland and wetland. By 2024, more than half the land is developed — paved or built on. The green bars shrank; the grey-blue bars grew. This is not nature changing slowly — humans changed it. When the grassland goes, the food web that lived there loses its base. Plants that used to capture sunlight and build food webs are gone. The carbon cycle and energy flow that ran through those ecosystems no longer happen there. How do human activities change energy and matter flow in ecosystems — and what happens as a result?
Notice & Wonder. Look at the chart. Write one thing you notice about which land type changed most — and one thing you wonder about what that means for the living things in that watershed.
Build it How humans redirect energy and matter at scale
Three connected ideas that link the data to what you already know from Weeks 1–3 and Unit 3.
Step 1 — Habitat loss cuts energy flow into food webs
Every patch of grassland, wetland, or forest is a solar energy capture system. Producers in that habitat convert sunlight into chemical energy that flows through the food web (Week 1 throughline). When that habitat is paved over or cleared, the solar capture stops. The energy pathway that once ran from sun → grass → insect → bird no longer exists. This is not just about losing one species; it is about cutting off an energy flow that supported dozens. At the local scale, one developer building one neighborhood removes one habitat. At the regional scale, thousands of such decisions add up to what the chart shows: grassland and wetland cut in half in 24 years. Scale, proportion, and quantity matter: a 10% habitat loss rarely triggers collapse; a 50%+ loss can push a food web past a tipping point from which recovery is very slow.
Every habitat is a solar energy capture system. Plants capture sunlight and send that energy up the food web. When habitat is paved over, that energy pathway stops. No plants = no energy entering the local web. One neighborhood matters a little. Thousands of neighborhoods together can cut the region's energy capture in half — that is what the chart shows. Scale matters: a small loss is recoverable; a large loss may not be.
Step 2 — Resource use, biodiversity loss, and climate connections
Humans affect ecosystems through three main pathways, all linked to energy and matter: (1) Resource extraction — harvesting materials (timber, water, soil nutrients) removes matter from ecosystems and breaks matter-cycling loops (Week 2). When topsoil is removed or a river is drained, the nutrient cycle that decomposers and plants depend on is broken. (2) Biodiversity loss — as habitats shrink, species with small ranges or specialized needs lose the critical area they need to maintain viable populations. Fewer species means fewer food-web connections, meaning less resilience to disturbance (Week 3). (3) Climate change — burning fossil fuels releases carbon that was locked underground (out of active cycling) for millions of years, flooding the atmosphere with CO₂. This connects to Unit 3: more CO₂ traps more heat in the atmosphere, warming the climate and changing precipitation patterns — which then alters which species can live where and how productive ecosystems are. These three pathways interact and amplify each other.
Humans affect ecosystems three main ways: (1) Using resources (cutting trees, diverting rivers) removes matter from the cycles that ecosystems need. (2) Reducing biodiversity — as habitats shrink, species disappear. Fewer species = fewer web connections = less ability to recover from disturbance. (3) Climate change — burning fossil fuels releases ancient carbon into the air as CO₂. More CO₂ warms the climate (Unit 3), which shifts what can live where. These three effects feed each other.
Step 3 — The throughline: humans redirect energy and matter at large scale
The crosscutting concept tying this to the whole year is Energy and Matter: in every unit we asked "where did the energy/matter go?" Human impact is the same question at a new scale. When we pave land, we redirect sunlight that would have powered photosynthesis into heating concrete instead. When we pump CO₂ into the atmosphere, we redirect carbon that was locked out of active cycling back into the global carbon cycle — at a rate far faster than decomposers or natural processes normally allow. When we remove a top predator through overhunting, we trigger a trophic cascade (Week 3) that reroutes energy and matter throughout the food web. Human actions do not violate conservation of energy or conservation of matter — those laws still hold. What we change is where the energy goes and how fast the matter cycles. And those redirections have consequences for every living thing connected to those flows.
Here is the year-long idea applied to human impact: humans redirect energy and matter. We move carbon from underground into the air. We block sunlight from reaching soil. We speed up or slow down matter cycling. Conservation of energy and matter still applies — the atoms and energy do not disappear. But we change their path and their speed. And those changes ripple through every food web on Earth.
Worked example — reading the watershed data and explaining one consequence (watch how an expert reasons)
Reading the data: From 2000 to 2024, grassland/wetland cover fell from 62% to 28% — a loss of 34 percentage points, or more than half the original area. Developed land rose from 14% to 52% — nearly quadrupling.
Connecting to energy flow (W1): The plants in that 34% of lost grassland no longer perform photosynthesis. Solar energy that used to enter the food web through those plants now heats concrete and asphalt instead. The food web lost its energy base.
Connecting to matter cycling (W2): Wetland soils cycle carbon and nitrogen. Paving a wetland seals carbon into the ground where it cannot be released by decomposers, and simultaneously destroys the decomposer community. Nutrient cycling slows or stops in those areas.
Connecting to trophic cascades (W3): With less habitat, populations of insects and amphibians decline — triggering top-down and bottom-up cascades through the remaining web.
Conclusion: the chart is not just a land-use record. It is a record of energy and matter flow being redirected away from the living system and into the built environment.
Show me a graphic organizer connecting the data to W1–W3 Tier 2 · organizer
Use this frame to connect the chart data to earlier lessons:
What the data shows: Grassland went from ___% to ___%, a loss of ___%. Developed land went from ___% to ___%, a gain of ___%.
Connection to W1 (energy flow): The lost grassland can no longer capture ________ energy. This means less energy enters the ________ and the food web at the ________ level.
Connection to W2 (matter cycling): Paving over wetlands stops ________ from breaking down matter. Carbon that was cycling through ________ is now locked under ________.
Connection to W3 (trophic cascades): As habitat shrinks, ________ species lose critical habitat and their populations ________. This triggers a ________ cascade through the food web.
Word bank: solar · food web · producer · decomposers · soil · concrete · insect · trophic · photosynthesis · carbon · biodiversity · cascade · limiting factor
Let's make it concrete first Tier 3 · re-teach
Analogy: Imagine a large kitchen that feeds a whole apartment building. Humans decide to shrink the kitchen by half — they wall off 50% of it and turn it into storage. The same number of people still live in the building, but now there is only half as much food being produced. People on the upper floors (top predators) start going hungry first. The cooks (decomposers) have less to work with. The building's community starts to break down — not because of a single dramatic event, but because the energy and matter inputs were cut. Paving over a habitat does the same thing: it shrinks the "kitchen" (the producer base) for the whole food web.
Fill in: When habitat is destroyed, plants that used to capture ________ energy can no longer do so. Less energy at the ________ level means ________ energy available for consumers. This is like shrinking the kitchen that ________ the whole building.
Say your answer aloud before writing it. Two sentences is enough.
Push my thinking Extension
Quantitative challenge: The watershed started with 62% grassland/wetland in 2000. Suppose each 1% of grassland supports 500 individual insects. In 2000 that is 31,000 insects in that 62% area. By 2024, with only 28% remaining, how many insects does the same relationship predict? What does a 55% reduction in insect population mean for the birds that eat them (use the 10% rule from W1)? Show your reasoning step by step.
Design challenge preview: What kind of human decision could reverse at least part of this trend? What would you need to know about the food web to design it well? Write three questions you would want answered before proposing a solution — and identify which week's science each question comes from. This previews next week's performance task.
Your turn Explain the human footprint
Use the data and your models to explain what happened in the watershed — and why it matters. Choose how you respond — all are equally valid.
The task: Using the bar chart data and your knowledge from Weeks 1–3, explain: (1) what changed in the watershed between 2000 and 2024; (2) how that change affected energy flow and matter cycling in the ecosystem; (3) whether the effects are local-only, regional, or both — and why; (4) one specific organism or group that would be affected by this change and why.
I want sentence frames and a word bank Tier 2 · frames
Claim: The watershed changed significantly between 2000 and 2024 because ________.
Evidence: According to the chart, grassland/wetland cover decreased from ___% to ___%, while developed land increased from ___% to ___%. This means ________.
Reasoning — energy: The lost habitat can no longer capture ________ energy through ________. This means less energy enters the ________ at the ________ level, which reduces energy available to ________.
Reasoning — matter: Paving over wetlands stops ________ from cycling ________ back into the ________, which means ________.
Scale: These effects are not just local because ________.
Affected organism: ________ would be affected because ________.
Word bank: solar energy · photosynthesis · producer · consumer · food web · matter cycling · decomposers · carbon · nutrients · soil · trophic cascade · biodiversity · habitat · local · regional · limiting factor · climate · CO₂
Let's make it concrete first Tier 3 · re-teach
Start with just the data: Look at the 2000 and 2024 bars for grassland/wetland. What happened — did the bar get taller or shorter? Now look at the developed-land bars. What happened there? Write down what you notice in your own words before trying to explain why.
Then connect one idea at a time:
Step 1 — Grassland went away. What does grassland do for energy flow? (Think W1: producers → consumers.)
Step 2 — Wetlands were paved. What do wetlands do for matter cycling? (Think W2: decomposers + nutrient cycling.)
Step 3 — Pick one organism — a bird, a frog, or an insect — and explain how losing 34% of the grassland/wetland would affect that organism's food or shelter.
Two to three sentences connecting each step is enough for a complete response. Say it out loud first.
Check yourself Did it click?
- read a bar chart showing habitat change and describe the trend using specific percentages;
- explain how habitat loss redirects energy flow and disrupts matter cycling in an ecosystem;
- distinguish local, regional, and global scales of human impact;
- connect human activities (resource use, biodiversity loss, climate change) to energy and matter flows from Weeks 1–3.
A classmate says: "Habitat loss only affects the animals that lived there — it's a local problem, and nature always bounces back eventually." Which response best addresses this reasoning?
Re-teach: human effects are not local-only, and recovery is not guaranteed Tier 3
Misconception 1 — "It's local only." Food webs are regional networks. A migratory bird that breeds in a local wetland spends the winter hundreds of kilometres away — its loss affects ecosystems in two regions. CO₂ released by clearing land mixes into the global atmosphere. Insect pollinators that depend on local grasslands support agriculture across whole counties. The effects of habitat loss travel through food web connections far beyond the site.
Misconception 2 — "Nature always bounces back." Small disturbances — a fire, a flood, even a drought — often allow ecosystems to recover because the foundational species survive and rebuild. But when habitat loss is large enough and sustained long enough (like the 34-percentage-point loss of grassland in our chart), populations of specialists can fall below minimum viable levels and go extinct locally. Once a species is gone from an area, the food web connections it maintained are permanently broken — there is no automatic recovery. Restoration requires deliberate human action, not just time.
Misconception 3 — "One person can't matter." This is true at the level of a single action, but human impact is cumulative. The chart does not show one person's decision — it shows the aggregate of thousands of individual land-use decisions over 24 years. The science of scale (CCC) says that individual effects, multiplied across populations and time, produce the large-scale patterns in the data.
Re-read option B. Try to say the three corrections in your own words before moving on.
Reflect, then show what you know
Reflection responsible decision-making + social awareness
Think about one human activity near where you live — construction, a road, agriculture, a park — that has affected a habitat. Using what you know from today, describe one energy or matter flow that changed as a result. You do not need to solve it — just describe what changed and connect it to a concept from this unit. Two to three sentences is enough.
Exit ticket — answer on paper or in your notebook. (2 new · 2 spiral · 1 transfer)
- New According to the chart, by approximately how many percentage points did grassland/wetland cover decrease between 2000 and 2024? Describe one consequence of that loss for energy flow in the food web.
- New Name the three main pathways through which humans affect ecosystems. For each, write one example of a specific human activity that causes that effect.
- Spiral — W2 When a wetland is paved over, what happens to the carbon that was being cycled through decomposers and plants in that wetland? Connect your answer to what you learned about matter cycling.
- Spiral — Unit 3 How does releasing large amounts of CO₂ into the atmosphere by burning fossil fuels connect to what you learned in Unit 3 about weather and climate? What does that mean for ecosystems?
- Transfer → W5 design task If your school decided to restore a degraded corner of the schoolyard as a habitat patch, what information about the local food web and energy/matter flows would you need before designing the restoration? Name at least three specific things you would want to know — and explain why each one matters for a successful design.
Educator panel — facilitation, accommodations, answer key, research rationale
At a glance
Standards: NGSS MS-ESS3-3 — Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment (introduced here; applied in W5). MS-ESS3-4 — Construct an argument supported by evidence for how changes to Earth's biodiversity impact the health of Earth as a system. Integrated with: MS-LS2-1 (factors affecting organism growth — habitat as a limiting factor), MS-LS2-4 (resource availability). 3D: SEP Analyzing & Interpreting Data + Constructing Explanations · DCI ESS3.C Human Impacts on Earth Systems + LS2.A Interdependent Relationships · CCC Cause & Effect + Energy & Matter + Scale, Proportion & Quantity. Year throughline: "Where did the energy/matter go?" — humans redirect these flows at large scale, which is the same CCC students have applied since Unit 1. This is the penultimate lesson before the year capstone; the exit ticket's transfer item explicitly seeds the W5 design task.
Materials needed: None required beyond paper and pencil. The bar chart is inline SVG — no external dependencies. Optional: print or display the chart separately so students can reference it during the practice task.
Estimated time: ~50 minutes. Data reading and build section: 15 min. Differentiated practice: 15 min. Self-check and re-teach: 5 min. Brain break, reflection, exit: 10 min. Do-Now: 5 min.
Facilitation arc (Rosenshine)
- Do-Now (5 min) — three items spiraling W1–W3 activate the three schema students need for today: 10% rule, energy vs. matter distinction, and trophic cascade logic. These will be applied directly to the human-impact content.
- Phenomenon — chart reading (5 min) — before revealing the worked example, ask: "What does 'developed land' mean for the organisms that used to live there?" Cold-call two students. Then ask: "If you know about energy flow from W1, what does a 34-point drop in grassland tell you about energy entering the food web?"
- Build Steps 1–3 + worked example (12 min) — pause after Step 1 and ask: "Can someone connect the grassland loss to a specific energy flow they traced in W1?" After Step 2: "Which of the three pathways (resource extraction, biodiversity loss, climate) do you think is hardest to reverse — and why?" After Step 3: "Is this a violation of conservation of energy? Explain."
- Differentiated practice (15 min) — circulate; look for students who treat the effects as purely local. Prompt: "Does this stop at the property line? What about a bird that nests here and feeds somewhere else?" Also watch for students who treat "nature bouncing back" as a universal law — prompt: "How big a loss is too big for automatic recovery?"
- Self-check + re-teach (5 min) — quick poll (A/B/C); route A/C responders to #reteach-impact.
- Brain break, reflection, exit (8 min) — the reflection is explicitly place-based (a real location near the student); this activates CRP (Gay, 2018) by grounding the abstract science in students' own environments. The exit ticket item 5 is the direct seed for W5 — do not skip it.
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); the simplified toggle shortens all passages. |
| Reduced reading load | "Reading: Simplified" swaps in shorter plain-language text throughout. |
| Chunking / extended time | Build section has three clearly numbered steps; chart reading is scaffolded in the Tier-2 organizer; progress saves automatically. |
| Sentence frames / word bank | Tier-2 panel provides CER frames for each step and a 13-term word bank for the practice task. |
| Concrete analogy / reduced load | Tier-3 "kitchen" analogy reduces the abstract ecosystem to a familiar system; guided step-by-step framing with simple chart-reading first before connecting to science. |
| Alternative response mode | Write a CER, draw a before/after ecosystem model, or record a narration — all accepted equally. |
| Behavior / focus (504, ADHD) | Named expectations (PBIS), 30-sec check-in, outdoor-visualization brain break with self-paced steps. |
| Multilingual / EL | Simplified text toggle, SVG chart with all series labeled in text (not color-only), word bank, home-language reflection allowed, place-based reflection prompt connects to student's own community. |
| IEP goal: data analysis | Tier-2 graphic organizer breaks chart reading into guided fill-in steps; students only need to read values off bars they can see, not interpolate. |
Exit ticket answer key
- Grassland/wetland decreased by approximately 34 percentage points (from 62% to 28%). Consequence: the plants in that lost area no longer perform photosynthesis — solar energy that used to enter the food web at the producer level no longer does. This means less energy is available to primary and secondary consumers throughout the regional food web.
- (1) Resource extraction — example: logging removes timber and breaks the nutrient cycle in forest soil; rivers diverted for irrigation remove water that wetland organisms depend on. (2) Biodiversity loss — example: habitat fragmentation from road-building isolates populations so they cannot interbreed, leading to local extinction. (3) Climate change — example: burning gasoline in cars releases CO₂ that was stored underground, adding it to the active carbon cycle and warming the atmosphere.
- When a wetland is paved, the decomposers (fungi, bacteria) and plant roots that were actively cycling carbon are killed or removed. The carbon that was in the soil and plant biomass is either sealed under concrete (slowing its release) or released rapidly as CO₂ during clearing and construction. Either way, the active matter-cycling loop in that wetland is broken — the decomposers can no longer convert organic matter back to CO₂ and nutrients for plants to absorb. (Conservation of matter: the carbon atoms are still somewhere, but they are no longer cycling through the living system.)
- Unit 3 taught that CO₂ and other greenhouse gases trap heat in the atmosphere, raising global temperatures and altering precipitation patterns. For ecosystems: higher temperatures can shift which species can survive in a given region (changing community composition), alter the timing of seasonal events like flowering and migration (breaking predator-prey timing), increase drought frequency (limiting water as a resource), and bleach coral reefs. The climate change connection also closes the loop on the carbon cycle from W2: humans are accelerating the release of carbon that was safely locked out of active cycling into the fast carbon cycle, destabilizing the balance between photosynthesis and respiration that ecosystems depend on.
- (Transfer — seeds W5.) Acceptable answers should name three of the following or similar: (a) What species currently live in or near the schoolyard — what are the producers, consumers, and decomposers? (Determines what food web connections could be restored.) (b) What habitat type is missing — grassland, wetland, woodland edge? (Determines what plant community to restore to maximize energy capture and food web support.) (c) What are the main limiting factors for the target species — water, nesting sites, food, soil nutrients? (Determines what restoration design elements are most important.) (d) What human activities are currently disrupting the site — foot traffic, chemicals, impervious surface nearby? (Determines what impacts must be addressed for the restoration to succeed.) (e) How does water and nutrient cycling currently work on the site — where does runoff go, is soil compacted? (Determines whether decomposer activity and plant establishment are feasible.) Each answer matters because a restoration that ignores the food web will not sustain itself; a design that plants the right species but misses limiting factors will fail.
Why it's designed this way
Data reading as SEP: MS-ESS3-3 and MS-ESS3-4 both require students to use data to support arguments about human impact. The bar chart is fictional but realistic — it represents a plausible regional habitat change pattern. Reading quantitative data from a chart before constructing an explanation is a core science practice (Achieve, 2013). The Tier-2 graphic organizer scaffolds the data reading explicitly, reducing the reading-to-reasoning load for students who need support.
Misconception targeting (re-teach panel): Research on environmental science learning consistently identifies three clusters of student misconceptions about human impact: (a) "effects are only local"; (b) "nature always recovers"; (c) "individual actions don't matter at the scale of a problem this big." The #reteach-impact panel directly addresses all three with specific scientific reasoning — not just counter-assertions. The goal is to give students the intellectual tools to engage with these arguments, not just to accept a conclusion.
Year-long CCC continuity: Every lesson in this curriculum has used "where did the energy/matter go?" as its organizing lens. Week 4 is the lesson where that lens is explicitly applied to human agency at scale — students discover that the same physics and chemistry that governed the hand-warmer (Unit 1), the food web (W1), the carbon cycle (W2), and the trophic cascade (W3) also explains why a parking lot matters for biodiversity. This is the CCC doing its intended work: helping students see that the same crosscutting concept applies across phenomena at different scales and contexts (NRC, 2012).
Transfer item design (exit ticket item 5): The final exit item is explicitly labeled as a preview of W5 and is designed as a genuine transfer task — students must apply what they know about food web science to a design problem they have not seen before. This creates a "desirable difficulty" (Bjork, 1994): students who struggle to answer it are being asked exactly the right question to make W5 more meaningful when they arrive at it.