Ecosystem Detectives Sub Plan Emergency Sub Plan • Zero Tech
Ecosystem Detectives
Grade 7 Life Science
Duration: 50–55 Minutes
Topic: Ecosystems & Trophic Cascades
Learning Objective (NGSS MS-LS2-1 & MS-LS2-2)
Students will construct an explanation that predicts how interactions among organisms (predation, competition, mutualism, commensalism, parasitism) and trophic cascades affect populations in an ecosystem.
Materials Needed
1 Student Packet per student
Regular pencils
Answer Key (for teacher/sub)
Lesson Flow & Time Allocations total 50 min
00–07 Min
Bellringer & Mission Briefing: Distribute packets.
Say to students: "Today you are ecological detectives investigating how removing a single predator can destabilize an entire wilderness. Write your name and start on the warm-up."
08–22 Min
Active Reading & Vocabulary Organizer:
Students read the Yellowstone case study independently or with a partner. They underline keywords and complete Graphic Organizer 1 (Symbiotic & Ecological Interactions Matrix) directly on Page 1.
23–40 Min
Trophic Flowchart & Critical Thinking Scenarios:
Students trace the cause-and-effect cascade on Page 2 and analyze 4 ecological challenge questions. Circulate the room to ensure students justify claims with evidence from the text.
41–50 Min
Exit Ticket & Collection:
Quiet, individual work on the 3-2-1 Exit Ticket at the bottom of Page 2. Collect all packets 2 minutes before the bell.
Support & Accommodations
Struggling readers: Pair with a peer to alternate paragraphs, or read the introductory paragraph aloud.
Sentence starters: Reference the bold definitions in the text to complete the matrix.
Fast Finisher Extension
Have early finishers flip to the back margin and sketch a secondary food web diagram showing what would happen to birds and fish if beavers disappeared again.
Substitute Teacher Daily Debrief Please leave this note for the returning teacher
Guest Teacher Name: ______________________
Date: ______________________
Notes on student engagement, absent students, or shout-outs:
Standby Science Quests • Lesson 1 Teacher Facilitation Page 1 of 1
Ecosystem Detectives Student Packet Life Science Field Dossier • Paper & Pencil
Ecosystem Detectives: The Yellowstone Mystery
Name:
Period:
Date:
Field Vocabulary Reference
Predation (+/-): One hunts and eats another.
Mutualism (+/+): Both organisms benefit.
Competition (-/-): Both battle for shared resources.
Commensalism (+/0): One benefits, one unaffected.
Parasitism (+/-): One lives on/in a host, causing harm.
Keystone Species: A critical species holding an ecosystem together.
Case File: The Domino Effect — How Wolves Changed Rivers Active Reading: Underline organism interactions as you read
In the 1920s, government bounty programs eradicated the gray wolf from Yellowstone National Park. Without this apex predator, the ecosystem spiraled out of control. Elk herds had no natural hunters and multiplied rapidly. They gathered in massive groups along fragile river valleys, browsing young willow, aspen, and cottonwood trees down to bare nubs. With the trees stripped away, riverbank soil eroded quickly into the water, clouding the rivers and washing away fish habitats.
Because tree saplings were eaten before they could grow, beavers had no lumber or food to build dams. The beaver population collapsed from dozens of colonies to just one. Songbirds lost nesting canopies, and shade-loving aquatic insects died off as shallow water warmed in the summer sun. What seemed like a simple removal of one predator had triggered a collapse across multiple trophic levels.
In 1995, wildlife biologists engineered a daring recovery plan: they reintroduced 14 gray wolves from Canada. The results were astounding. Wolves immediately began hunting elk, but more importantly, their presence changed elk behavior. Elk avoided open valleys and narrow gorges where they could be easily trapped. Within a few short years, willow trees quadrupled in height.
With trees returning, beavers recolonized the rivers. Beaver ponds created habitats for otters, ducks, amphibians, and native trout. Tree roots locked soil in place, causing meandering rivers to stabilize and clear. The return of a single keystone species caused a trophic cascade—an ecological chain reaction that restored balance from predators all the way down to the physical landscape itself.
Graphic Organizer 1: Interaction Detective Matrix
Classify each ecological pairing. Write the relationship type, symbols (+, -, or 0), and evidence on the ruled lines.
Organisms Interacting Relationship Type Effect (A/B) Evidence / Why? 1. Gray Wolf & Elk
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| 3. Beavers & River Fish |
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| 4. Ticks on an Elk's Hide |
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Standby Science Quests • Yellowstone Case Study Page 1 of 2
Part 2: Trophic Cascade Chain Reaction
Name: Period:
Summarize the domino effect of reintroducing wolves. Write on the ruled lines in each box below.
1 Apex Predator
14 wolves reintroduced
2 Primary Herbivores
Elk population & habits
3 Producers
Willows & river trees
4 Landscape & Others
Beavers, rivers, soil
Part 3: Ecological Investigation Questions
1. Why is the gray wolf classified as a keystone species rather than just a regular predator? Use evidence from the text to justify your answer.
2. Both coyotes and wolves hunt small rodents. When wolves returned, coyote populations dropped by 50%. What type of interaction is this, and why did it happen?
3. Predict: If a severe bacterial disease wiped out 90% of the beaver population next year, what would happen to the riverbanks and fish populations? Explain your reasoning.
Part 4: 3-2-1 Exit Ticket Pencil Only
3 Things I Learned Today:
2 Examples of Symbiotic or Ecological Relationships from Class:
1 Big Question I Still Have About Ecosystems:
Standby Science Quests • Ecosystem Analysis & Exit Ticket Page 2 of 2
Ecosystem Detectives Answer Key Teacher & Sub Evaluation Key
Ecosystem Detectives Answer Key
Grade 7 Life Science
Total Points: 25 Pts
Part 1: Interaction Matrix Key (8 Pts — 2 pts each) Accept reasonable phrasing
Organisms Relationship Type Effect (A/B) Expected Evidence / Explanation 1. Wolf & Elk Predation (+ / -) Wolves hunt and consume elk for energy; elk lose life/fitness. 2. Elk & Willows Herbivory / Predation (+ / -) Elk gain nutrients; willow saplings are stripped, damaged, or killed. 3. Beavers & Fish Commensalism / Mutualism (+ / 0) or (+ / +) Beaver dams create deep, cool pool habitats for fish to thrive. 4. Ticks & Elk Parasitism (+ / -) Ticks feed on elk blood (gain nourishment); elk suffer blood loss and irritation.
Part 2: Trophic Cascade Flowchart Key (4 Pts — 1 pt per stage)
Step 1: Wolves
14 wolves reintroduced; establish territories and hunt elk herds.
Step 2: Elk
Populations stabilize; elk avoid open valleys & stop overgrazing riverbanks.
Step 3: Willows
Willow and aspen saplings grow tall; dense root systems lock stream soils.
Step 4: Rivers & Beavers
Beavers build dams; water clears; bird and trout habitats recover.
Part 3: Critical Thinking Scenarios Key (9 Pts — 3 pts each)
Q1 (Keystone Species): Wolves exert a disproportionately large effect on the entire ecosystem compared to their low population numbers. Removing wolves caused the entire ecosystem structure (plants, herbivores, rivers) to collapse, proving they anchor the balance.
Q2 (Coyote Competition): This is interspecific competition (-/-). Wolves and coyotes compete for shared territory and food. Because wolves are larger and more dominant, they reduced coyote access to prey and aggressively defended territory.
Q3 (Disease Prediction): Without beavers maintaining dams, pond water would drain, reducing wetland habitats. Fish and amphibians would lose breeding grounds, and river currents would flow faster, increasing bank erosion.
Part 4: 3-2-1 Exit Ticket Scoring (4 Pts)
3 Things Learned (2 pts): Must list 3 distinct, accurate facts about wolves, trophic cascades, or plant recovery.
2 Relationships (1 pt): Correctly names 2 pairs with proper ecological classification (e.g. Wolf/Elk = Predation).
Matter Transformers Sub Plan Emergency Sub Plan • Zero Tech
Matter Transformers
Grade 7 Physical Science
Duration: 50–55 Minutes
Topic: Physical vs. Chemical Changes
Learning Objective (NGSS MS-PS1-2 & MS-PS1-5)
Students will analyze and interpret data on observable properties of substances to distinguish between physical and chemical changes, identifying signs of chemical reactions and verifying the law of conservation of mass.
Materials Needed
1 Student Packet per student
Regular pencils
Answer Key (for teacher/sub)
Lesson Flow & Time Allocations total 50 min
00–07 Min
Bellringer & Concept Hook: Distribute packets.
Say to students: "Look around this room. Matter is constantly being rearranged. Today you will learn how to spot whether atoms are just changing outfits (physical) or transforming into brand-new substances (chemical)."
08–22 Min
Reading Passage & Concept Organizer:
Students read "The Kitchen Lab Mystery" and review the 5 Clues of a Chemical Change. They complete the Graphic Organizer on Page 1 comparing physical versus chemical properties and changes.
23–40 Min
Evidence Practice & Conservation of Mass:
Students classify 6 real-world scenarios on Page 2 and solve the two conservation of mass math challenges. Walk around to prompt students: "What observable clue tells you a new substance was created?"
41–50 Min
CER Exit Ticket & Collection:
Students complete the Claim-Evidence-Reasoning Exit Ticket about a burning candle. Collect all student packets before dismissal.
Support & Accommodations
Memory Mnemonic: Remind students of the acronym "City Girls Love Their Phones" (Color, Gas, Light, Temperature, Precipitate).
Sentence Stems: "I know this is chemical because I observe ______."
Fast Finisher Extension
Have fast finishers write a 3-sentence mystery scenario of their own on the back margin and challenge a neighbor to classify it as physical or chemical.
Substitute Teacher Daily Debrief Please leave this note for the returning teacher
Guest Teacher Name: ______________________
Date: ______________________
Notes on student engagement, absent students, or shout-outs:
Standby Science Quests • Lesson 2 Teacher Facilitation Page 1 of 1
Matter Transformers Student Packet Physical Science Lab Brief • Paper & Pencil
Matter Transformers: Physical vs. Chemical Changes
Name:
Period:
Date:
The 5 Signs of a Chemical Reaction Memory Clue: "City Girls Love Their Phones"
Color Change
Gas / Bubbles
Light Produced
Temp Change
Precipitate (Solid)
Investigation: The Kitchen Chemistry Lab Active Reading: Underline physical changes and circle chemical changes
You don't need a high-tech laboratory to observe the transformations of matter. Every morning in the kitchen, ordinary materials undergo profound changes. When you slice an apple, you exert a force that alters the apple’s shape and size. However, the molecules making up the apple remain chemically identical. This is a physical change: the appearance changes, but no new chemical substance is formed. Other physical changes include melting butter in a warm pan (a solid becoming a liquid) or dissolving table sugar into water (the molecules disperse, but remain sugar).
Leave that sliced apple on the counter for thirty minutes, however, and something new happens. Enzymes inside the fruit react with oxygen in the air, creating melanin pigments that turn the apple flesh dark brown. This oxidation is a chemical change. In a chemical change, chemical bonds between atoms break and reform in new arrangements, producing entirely new substances with brand-new properties.
Consider making pancakes. Mixing flour, milk, and eggs is a physical blending of ingredients. But when the wet batter pours onto a hot 375°F skillet, heat triggers chemical reactions. Baking powder produces expanding carbon dioxide gas bubbles, making the pancake fluffy. Proteins and sugars undergo the Maillard reaction, transforming golden-white batter into aromatic, brown cakes that cannot be turned back into raw batter.
Crucially, matter can never be magically created or destroyed. According to the Law of Conservation of Mass, every atom that existed before a transformation must still exist afterward. Even if gas escapes into the room or smoke drifts into the air, the total mass of the reactants always equals the total mass of the products!
Graphic Organizer: Matter Transformation Comparison Matrix
Feature Physical Change Chemical Change 1. Definition
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Matter Transformers Answer Key Teacher & Sub Evaluation Key
Matter Transformers Answer Key
Grade 7 Physical Science
Total Points: 25 Pts
Part 1: Concept Matrix Key (6 Pts) Accept equivalents
Criterion Physical Change Chemical Change Definition Alters appearance, shape, or state; chemical composition stays identical. Bonds break and reform; creates one or more brand-new substances. New Substance? No (Same molecules) Yes (New chemical identity) Reversibility? Usually easily reversed (e.g., refreezing liquid water). Difficult or impossible to reverse by physical means. Examples Melting ice, tearing paper, dissolving sugar, boiling water. Baking bread, rusting iron, burning wood, battery discharging.
Part 2: Evidence Detective Key (6 Pts — 1 pt each)
1. Rusting nail: Chemical — Color change (red-brown) and formation of new compound (iron oxide).
2. Freezing water: Physical — State change (liquid to solid); chemical formula is still \(H_2O\).
3. Baking soda + vinegar: Chemical — Gas production (carbon dioxide bubbling) & temperature drop.
4. Shredding paper: Physical — Change in size and shape only; cellulose fibers remain unchanged.
5. Fireworks: Chemical — Intense light, loud sound, heat release, odor, and smoke produced.
6. Dissolving sugar: Physical — Dissolution/mixture; evaporating water recovers dry sugar crystals.
Part 3: Conservation of Mass Key (6 Pts — 3 pts each)
Case A (Closed Flask): Exactly 115 grams (\(100\text{g} + 15\text{g} = 115\text{g}\)).
Because the container was completely sealed, the carbon dioxide gas produced could not escape into the atmosphere. The total mass of reactants equals the total mass of products.
Case B (Open Fireplace): No, zero mass was destroyed.
The burning reaction released 45 grams of matter as gaseous smoke, carbon dioxide (\(CO_2\)), and water vapor (\(H_2O\)) into the room. If captured in a closed chamber, total mass would remain conserved.
Part 4: CER Exit Ticket Rubric & Model Answer (7 Pts)
Claim (2 pts): A burning candle exhibits both physical and chemical changes.
Evidence (2 pts): Solid wax near the flame melts into clear liquid wax and resolidifies as it drips down. Meanwhile, the wick turns black, a flame produces light and heat, and smoke/gas rises.
Reasoning (3 pts): Melting wax is a physical change because it only changes phase (solid to liquid) without altering chemical structure. The burning wick and combusting vaporized wax is a chemical change because hydrocarbons react with oxygen to form new substances (\(CO_2\) and \(H_2O\)), releasing heat and light energy.
