UNIT OVERVIEW: This 7–9 day unit investigates how feedback mechanisms increase or decrease changes, stabilizing or destabilizing climate systems and altering Earth's temperatures. PERFORMANCE EXPECTATIONS: HS-ESS2-2, HS-ESS2-4, HS-ESS2-6 CCC FOCUS: #7 Stability and Change (rates of change) and #2 Cause and Effect INVESTIGATIVE PHENOMENON: The globe is warming, and the average temperature of the Arctic is increasing at almost 4 times the rate as the rest of the globe. PRIOR KNOWLEDGE: Students have already learned that orbital factors (Milankovitch cycles) caused past climate changes. This unit addresses current warming that cannot be explained by orbital factors.

PHASE GOAL: Students analyze a graph of temperature changes across the globe to identify the investigative phenomenon and generate driving questions. GROUPING: None (whole class) TIMING: ~1 class period MATERIALS: "We are Warming" handout, Driving Question Board ROUTINE: Rumors — students share initial ideas informally TRANSITION: Students' ideas about greenhouse gases and ice will drive the Explore 1 investigation.

TEACHER MOVE: Display the temperature anomaly map. Before taking answers, let students observe quietly for 30 seconds. Then use the Rumors routine to let students share ideas informally. EXPECTED STUDENT RESPONSES: Greenhouse gases are related to warming; Carbon dioxide causes warming; Human activities cause warming; Ice melting makes the Arctic warm faster. DISCUSSION POINTS: Don't correct misconceptions yet — capture all ideas on the DQB. Common misconceptions: students may mention the ozone hole (not the same as greenhouse effect). Note which students connect to prior learning about orbital factors. TRANSITION: "Many of you mentioned greenhouse gases and CO₂. Let's investigate whether there really is a causal relationship between CO₂ and temperature."

PHASE GOAL: Students develop and use models to gather evidence about the causal mechanism behind the correlation between atmospheric CO₂ and climate factors like temperature. GROUPING: Table groups TIMING: ~2 class periods MATERIALS: Carbon Dioxide and Air Temperature Investigation handout, Making Sense handout, calculators, PhET Greenhouse Effect simulation ROUTINE: Domino Discover CCC FOCUS: #7 Stability and Change — rates of change. Use conferring prompts to push students toward quantifying rates.

TEACHER MOVE: Before students begin Part 1, surface high-level observations of the graphs. Ask: "What do you notice?" Let 3-4 students share. Don't confirm or deny ideas — just capture them. EXPECTED STUDENT RESPONSES: "They go up and down together." "When one is high, the other is high." Some may say CO₂ "causes" temperature changes — note this but don't confirm yet. KEY POINTS TO SURFACE: The pattern is cyclical over 800K years. CO₂ ranged from ~180-300 ppm naturally. The relationship is consistent but doesn't prove direction of causation yet. TIMING: 5-7 minutes for initial observation and discussion.

TEACHER MOVE: Walk students through the rate calculation for the first one, then let them do the second independently or in pairs. Circulate and check calculations. EXPECTED STUDENT RESPONSES: Students may struggle with the scale — 7,000 years vs 200 years. Help them understand that "rate of change" means how fast something is changing per unit of time. COMMON MISCONCEPTIONS: Students may think rates were always constant. Emphasize that natural rates varied but were always MUCH slower than the current rate. KEY POINTS TO SURFACE: The speed of change is the critical evidence. Natural processes cannot explain this rapid increase. CONFERRING QUESTIONS: "What does it mean that the rate is 50-80x faster? What could cause such a dramatic acceleration?" TIMING: ~15 minutes for calculations and discussion.

TEACHER MOVE: Have students use these tables to draw a quantitative model (diagram with arrows showing flows) and then calculate net changes for each reservoir. EXPECTED STUDENT RESPONSES: Students should find the system is roughly in balance — atmosphere net change ≈ 0 Gt/yr. Small imbalances exist (+2 land, -2 ocean) but overall the system is stable. KEY POINTS TO SURFACE: Fossil fuels contribute ZERO carbon to the atmosphere in the pre-industrial model. The carbon cycle is balanced — what goes in roughly equals what comes out. CONFERRING QUESTIONS: "What does it mean when net change is zero? Is the system stable or changing?" TIMING: ~15-20 minutes for model building and calculations.

TEACHER MOVE: Have students calculate net changes. Key result: Atmosphere gains +5 Gt/year. Even though ocean and land absorb more, they can't keep up with fossil fuel emissions. EXPECTED STUDENT RESPONSES: "The atmosphere is gaining carbon." "Fossil fuels are losing carbon." "The system is not balanced anymore." KEY POINTS TO SURFACE: The NEW flow (Fossil Fuels → Atmosphere at 10 Gt/yr) is what disrupted the balance. The atmosphere net gain of +5 Gt/yr means CO₂ is accumulating. COMMON MISCONCEPTIONS: Students may think the ocean/biosphere can "absorb it all eventually." Clarify that sinks are increasing but not fast enough to offset the new source. TIMING: ~15-20 minutes for model building and calculations.

TEACHER MOVE: Use the Domino Discover routine to surface important observations. Ask groups to share one key difference between pre- and post-industrial models. EXPECTED STUDENT RESPONSES: "The amount of carbon moving from fossil fuels increased." "There's more carbon in every system except the geosphere." "The system is not in balance anymore." DISCUSSION FACILITATION: Record student observations on chart paper. Guide toward the conclusion that human activity created a NEW carbon flow that destabilized the system. TRANSITION: "Now let's investigate what all this extra CO₂ actually does in the atmosphere. We'll use a simulation to explore the mechanism."

TEACHER MOVE: Have students use the PhET Greenhouse Effect simulation ("Waves" tab). First set GHG to "none" and start sunlight. Then slowly increase. CONFERRING QUESTIONS: "Where is the energy coming from? How does the energy change form when it hits Earth's surface? How does the energy react as greenhouse gas levels rise?" KEY POINTS TO SURFACE: Sunlight → absorbed by surface → re-emitted as infrared → trapped by GHG molecules → re-emitted toward surface → warming. This is the MECHANISM. COMMON MISCONCEPTIONS: Students may think GHGs block sunlight (they don't — they trap heat). Some may think heat is "created" — it's just retained longer. TIMING: ~20-25 minutes for simulation exploration.

PHASE GOAL: Students construct an explanation using empirical evidence from data, models, and text, describing how human activities have caused greenhouse gas levels to increase and their impact on climate. GROUPING: Triads (for reading/annotation), then individual, then whole class TIMING: ~2 class periods MATERIALS: The Enhanced Greenhouse Effect handout, The Greenhouse Effect text, Burning Fossil Fuels text, Class Consensus Discussion steps, chart paper ROUTINES: Think-Talk-Open Exchange (first time!), Class Consensus Discussion CCC FOCUS: #2 Cause and Effect — using empirical evidence to establish causal claims

TEACHER MOVE: Have students work in triads on Part 1. Key question: Would natural CO₂ fall within the historical range? (Yes — 286.68 ppm is within 180-300 ppm.) What does the extra 134.91 ppm do? (Traps more heat via greenhouse effect.) EXPECTED STUDENT RESPONSES: Students should recognize that without human activity, CO₂ would be "normal." The additional human-caused CO₂ is what's driving the enhanced greenhouse effect. TRANSITION: After Part 1, show the video "Evidence Links Human Activity to Global Warming" from PBS LearningMedia. TIMING: ~15 minutes for triads to complete Part 1.

TEACHER MOVE: Students should have read The Greenhouse Effect text. Review the mechanism. Clarify the analogy: like a puffy coat trapping body heat, or a hot car — sunlight enters, is converted to heat, and is trapped. KEY POINTS TO SURFACE: The greenhouse effect is not inherently bad — without it, Earth would be frozen. The ENHANCED greenhouse effect from extra CO₂ is the problem. COMMON MISCONCEPTIONS: "Greenhouse effect" ≠ "bad." Students may confuse the natural greenhouse effect (good) with the enhanced greenhouse effect (problematic). TIMING: ~10 minutes for review and discussion.

TEACHER MOVE: Students should have read the Burning Fossil Fuels text. Use these numbers to build a sense of scale. The balloon analogy is powerful — 1,100 balloons from ONE gallon. KEY POINTS TO SURFACE: The Industrial Revolution (1760-1840) was the turning point. Emissions have only accelerated since. The carbon cycle used to be balanced; now it's not. DISCUSSION FACILITATION: Ask students to estimate their family's contribution. How many gallons of gas per week? How many balloons of CO₂? TRANSITION: "Now you have the evidence. Let's construct a scientific argument."

TEACHER MOVE: Facilitate Think-Talk-Open Exchange routine. Steps: (1) Students brainstorm individually. (2) Share with a partner — find similarities and differences. (3) Open exchange in triad — piece together disparate information. (4) Individually outline CER. (5) Write argument. CONFERRING QUESTIONS: "What evidence are you using? Where did it come from? How does it connect to your claim? What logical reasoning connects the evidence to your claim? Is there additional evidence?" CCC CONNECTION: #2 Cause and Effect — empirical evidence about CO₂ changes AND the greenhouse effect mechanism together support a CAUSAL relationship. TIMING: ~30-40 minutes for brainstorm, exchange, and writing.

TEACHER MOVE: Facilitate Class Consensus Discussion. Post chart paper: "Class Consensus: How Human Activities Cause the Enhanced Greenhouse Effect." Select 2-3 groups to share. Record agreed-upon ideas. Then have students complete the Summary Task independently. KEY POINTS TO SURFACE: (1) Matter conservation — carbon moves, isn't created. (2) Energy conservation — energy changes form, isn't created. (3) Rates of change prove human cause. (4) Mechanism (greenhouse effect) proves causation. TRANSITION: "We've established that humans are causing warming through CO₂. But we still haven't explained why the Arctic is warming 4x faster. What's special about ice?"

PHASE GOAL: Students analyze models and datasets of surfaces on Earth to figure out how different surfaces change the surrounding system and impact temperature. GROUPING: Table groups TIMING: ~1-2 class periods MATERIALS: Ice and Radiation handout, lab supplies (4 jars, colored construction paper, thermometers, heat lamp, timer), Sea Ice Extent spreadsheet ROUTINE: Domino Discover RESOURCES: "How hot is asphalt or cement in summertime?" video, "Documenting Glacial Change" PBS video, Google Sheets graphing tutorial

TEACHER MOVE: If weather permits, take students outside for 10 minutes to touch and measure surfaces. Otherwise, show the YouTube video on asphalt/cement temperatures. EXPECTED STUDENT RESPONSES: "Dark things are hotter." "White/light things are cooler." Some may connect to wearing black vs. white clothes in summer. TRANSITION: "Let's test this more carefully with a controlled experiment." TIMING: 10-15 minutes.

TEACHER MOVE: Students set up and run the experiment in table groups. Circulate and confer. Expected results: Black > Green ≈ Blue > White for final temperature. CONFERRING QUESTIONS: "Why is the black jar hottest? What does the color of the paper tell us about what's happening to the light energy? How does this connect to Earth's surfaces?" KEY POINTS TO SURFACE: This is a model of what happens on Earth — ice/snow (white) reflects light, ocean/land (dark) absorbs it. When ice melts, the surface underneath is darker. TIMING: ~35-40 minutes including setup, data collection, and graphing.

TEACHER MOVE: Students open the Google Sheets spreadsheet and create line graphs of each dataset. Then analyze trends and relationships. EXPECTED STUDENT RESPONSES: Students should identify the inverse relationship between temperature/heat and ice. Some may begin to use the term "feedback loop" from prior knowledge. DISCUSSION POINTS: How are these four variables connected? What happens first? Does one cause the other, or do they reinforce each other? TRANSITION: "You've shown that darker surfaces absorb more heat. Ice is disappearing while temperatures rise. In the next phase, we'll put a name to this mechanism and build a complete model."

PHASE GOAL: Students construct an explanation for how positive feedback loops related to the albedo effect are causing the Arctic to warm much faster than the rest of the planet. GROUPING: Independent → pairs → table groups → whole class TIMING: ~1-2 class periods MATERIALS: Ice Caps and Global Temperatures handout, Summary Task, cause-and-effect card sort, Class Consensus Discussion steps, chart paper ROUTINES: Card Sort, Class Consensus Discussion LITERACY STRATEGY: Cause-and-Effect Chart RESOURCES: "Earth's Albedo and Global Warming" PBS LearningMedia, "The Rise and Fall of Ice Age Glaciers" video

TEACHER MOVE: Introduce the term "albedo" formally. Show the PBS LearningMedia resource (Introduction and Ice-Albedo Feedback tabs). Ask students to describe the albedo effect in their own words. EXPECTED STUDENT RESPONSES: "Albedo is how reflective something is." "Ice is like a mirror for sunlight." "When ice melts, the mirror goes away." KEY POINTS TO SURFACE: The difference between ice (~0.6) and ocean (~0.06) is enormous — a 10x difference in absorption. This is why ice loss has such a large effect. TIMING: ~10-15 minutes for introduction and discussion.

TEACHER MOVE: Students work with card sort pieces to build this cause-and-effect sequence. Then individually summarize in their handout. Select 2-3 groups to share during Class Consensus Discussion. EXPECTED STUDENT RESPONSES: Students should construct the loop showing warming → melting → less reflection → more warming → more melting. CCC CONNECTION: #7 Stability and Change — positive feedback loops DESTABILIZE systems. If ice expands, more radiation reflects → cooling → more ice (and vice versa). The system amplifies changes. CONFERRING QUESTIONS: "What would happen if temperatures decreased instead? Would the loop work in reverse?" TIMING: ~20-25 minutes for card sort and individual writing.

TEACHER MOVE: Facilitate Class Consensus Discussion. Post chart paper: "Class Consensus: How Ice Impacts Radiation Reaching Earth." Have 2-3 groups share card sort models. Record agreed-upon ideas. Guide toward the complete explanation above. KEY POINTS TO SURFACE: The Arctic isn't warming faster because it gets more CO₂ — it warms faster because the ice-albedo feedback loop amplifies warming more there than anywhere else. TRANSITION: After consensus, students complete the Summary Task. Then transition: "We've identified TWO feedback loops — greenhouse effect and albedo. But there's more to the story..."

TEACHER MOVE: Students complete the Summary Task independently. Confer to push students toward the idea that positive feedback loops cause ACCELERATING rates of change — the system is destabilizing. KEY POINTS TO SURFACE: The rates of change are not constant — they're getting faster. This is the signature of positive feedback loops at work. CCC CONNECTION: #7 Stability and Change — feedback loops determine whether a system stabilizes or destabilizes. All the feedback loops we've identified are POSITIVE (amplifying), meaning the system is destabilizing.

PHASE GOAL: Students model the combined effects of greenhouse gas and albedo feedback loops to explain the rapid rate of change and predict future impacts. GROUPING: Table groups TIMING: ~1-2 class periods MATERIALS: Greenhouse Gas Feedback Mechanisms handout, laptops, card sort from Explain 2 (+ 2 new cards) ROUTINE: Think-Talk-Open Exchange KEY CONCEPT: Temperature and CO₂ have a BIDIRECTIONAL relationship. CO₂ causes warming (greenhouse effect) AND warming causes CO₂ to rise (feedback through oceans, biosphere, cryosphere).

TEACHER MOVE: Pose the question: "If the cause and effect is so clear, what evidence do skeptics use?" Show the graph where temperature leads CO₂. Let students brainstorm — the answer will come from the next activity. EXPECTED STUDENT RESPONSES: "Maybe something else caused the warming first." "Maybe the warming released CO₂." Both are correct — in natural cycles, orbital changes initiated warming, which then released CO₂, which caused more warming. KEY POINTS TO SURFACE: This is NOT a contradiction — it's evidence of feedback loops. The skeptic argument is a false dichotomy. TIMING: ~10 minutes for brainstorming and initial discussion.

TEACHER MOVE: Students read the table in their handout, then use it to complete the carbon movement model (arrows showing flow when temperatures increase vs. decrease). KEY POINTS TO SURFACE: ALL three systems release more CO₂ when it warms, and absorb/trap more when it cools. This creates a powerful positive feedback loop. COMMON MISCONCEPTIONS: Students may think plants just "absorb more CO₂ when it's warm" — clarify that BOTH photosynthesis AND respiration/decay increase, but the net effect is more CO₂ released because decomposition and soil respiration increase faster. TIMING: ~15-20 minutes for reading and model completion.

TEACHER MOVE: Students add 2 new cards to their cause-and-effect model from Explain 2, incorporating the greenhouse gas feedback loop. Facilitate Think-Talk-Open Exchange about how feedback mechanisms affect future climate. EXPECTED STUDENT RESPONSES: Students should recognize that the two loops reinforce each other, creating accelerating change. Future predictions should reference both loops. DISCUSSION FACILITATION: "How did the results of the card sort demonstrate the role of feedback mechanisms? How could that impact climate change in the future?" TIMING: ~25-30 minutes for card sort extension and Think-Talk-Open Exchange.

PHASE GOAL: Students analyze data to make a valid claim about the role human activities are playing in causing destabilizing feedback loops that cause climate change. GROUPING: Small groups → individual TIMING: ~1 class period MATERIALS: Disprove the Skeptics handout, Climate Feedbacks Rubric ROUTINE: Domino Discover

TEACHER MOVE: Students work independently or in small groups on the Disprove the Skeptics handout. They label the ice core graph for places where CO₂ leads vs. temperature leads. Then analyze current data showing CO₂ is leading today. CONFERRING QUESTIONS: "What evidence did you generate in this 5E sequence? Where did it come from? How well does it support the claim? What contradictory evidence weakens it?" KEY POINTS TO SURFACE: The current situation is different from natural ice age cycles. Humans are the initiating cause. Both positive feedback loops then amplify the warming. TIMING: ~30-40 minutes for analysis and writing.

TEACHER MOVE: Review the rubric with students before they write. Proficient responses include ALL five components. Developing responses include some but not all. KEY DISTINCTION: Proficient = evidence linked using scientific logic and reasoning. Developing = evidence present but not well connected. Cause & Effect component: Students must clearly articulate the causal link between ice caps/ocean currents and arctic amplification. TIMING: ~30-40 minutes for individual writing.

TEACHER MOVE: Use the DQB Routine. Have students identify answered questions (move to "Figured Out" column). Identify remaining questions. Add new ones. KEY TRANSITION: Highlight that we now know HOW climate change happens (past and present), but we haven't addressed the skeptic who says "climate change isn't a big deal." This drives the next learning sequence. TIMING: ~10-15 minutes for DQB review and discussion.

TEACHER NOTES: This slide serves as a study reference. Students should be using these terms in their explanations and written arguments throughout the unit. Pay attention to whether students distinguish between the natural greenhouse effect (beneficial) and the enhanced greenhouse effect (problematic).

TEACHER NOTES: Rate of change and the correlation vs. causation distinction are central to this unit. Students should be able to explain WHY we can claim causation (we have a mechanism + empirical evidence + rate-of-change analysis), not just that the two variables are correlated.