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Science CER
Urban Heat Island: Pavement vs. Green Space
Grade 7 NGSS SEP4, SEP6, SEP7; CCSS.WHST.6-8.1 6 steps

What to Do

  1. Read the Investigation Question carefully.
  2. Study the Background Information and Data Table.
  3. Review the Key Vocabulary — use these words in your writing.
  4. Complete each writing step. Use evidence from the data to support your answer.
  5. In your rebuttal, explain why the Alternative Explanation is not supported by the data.
  6. Use the checklist at the end to review your work.

Investigation Question

How does the type of ground cover (pavement vs. grass vs. tree canopy) affect surface and air temperatures in a city neighborhood?

Background Information

Urban heat islands occur when cities are significantly warmer than surrounding
rural areas. This happens because cities replace natural land cover (grass, trees,
soil) with materials like asphalt and concrete that absorb and hold more heat.

Albedo is the measure of how much sunlight a surface reflects. A surface with high
albedo reflects more sunlight and stays cooler. A surface with low albedo absorbs
more sunlight and heats up more.

Scientists in this investigation measured surface and air temperatures (at 1 meter
height) in three city blocks with identical solar exposure, on a sunny summer day
at 2:00 PM.

Temperature by Ground Cover Type (Summer, 2:00 PM)

Ground CoverSurface Temp (°C)Air Temp at 1m (°C)Albedo (%)
Asphalt pavement58365%
Concrete sidewalk493325%
Grass lawn322820%
Urban forest / tree canopy242515% (canopy) + shade
All measurements taken at the same time of day and same solar angle. Air temp measured at 1m above surface.

Alternative Explanation (for your Rebuttal)

"The temperature differences could be due to differences in building density or air conditioning waste heat, not the ground cover type itself"

Key Vocabulary
WordDefinition
urban heat island The phenomenon where urban areas are significantly warmer than surrounding rural areas due to human modification of land cover
albedo The fraction of sunlight reflected by a surface — high albedo (white/light surfaces) stay cooler; low albedo (dark surfaces) absorb more heat
heat absorption The process of a surface taking in solar energy and converting it to heat — dark materials absorb more
evapotranspiration The process by which plants release water vapor through their leaves, cooling the surrounding air
thermal mass The ability of a material to absorb and store heat — asphalt has high thermal mass and releases stored heat slowly
Writing Steps
1 Examine the Evidence
Answer these questions to show you understand the data:

1. What is the investigation question asking you to explain?
2. What is the independent variable? The dependent variable?
3. What trend or pattern do you see in the data? (Be specific — use numbers.)
4. Can you think of an alternative explanation for the data? What else could cause this result?

Bullet points or short sentences are fine.
Before writing, carefully read the investigation question and analyze the data.

Scientists read data critically before forming explanations. Look for:
- Patterns and trends in the numbers
- Which variables were controlled and which were tested
- What the data shows and what it doesn't show
- What alternative explanations a skeptic might propose

Note: This step prepares you to write. It is not part of your final score.
Scoring Guidance — Step 1
Look for:
  • Independent variable = what was changed. Dependent variable = what was measured.
  • Note specific values: the highest, lowest, the difference between conditions
  • Think like a skeptic: could anything else explain this pattern?
Claim
Evidence
Reasoning
Rebuttal
2 Write Your Claim
Write one precise sentence that answers: How does the type of ground cover (pavement vs. grass vs. tree canopy) affect surface and air temperatures in a city neighborhood?

Make sure your claim:
- States a specific relationship between two variables
- Uses precise scientific language
- Could be tested or proven wrong with data
A claim is one precise sentence that directly answers the investigation question.

Investigation Question: How does the type of ground cover (pavement vs. grass vs. tree canopy) affect surface and air temperatures in a city neighborhood?

A strong claim:
- Answers the question in ONE sentence
- Is precise and measurable
- Names the direction of effect
- Is falsifiable — it could be tested or proven wrong
Scoring Guidance — Step 2
Role: claim
Target: ~20 words
Look for:
  • Name both variables: what was changed AND what was measured
  • State the direction: as X increases, Y increases/decreases
  • Avoid vague language: 'affected it' → name the specific effect
Name both variables: what was changed AND what was measured
State the direction: as X increases, Y increases/decreases
Avoid vague language: 'affected it' → name the specific effect
Sentence Starters
My claim is that ___ affects ___.
Based on the data, ___.
The investigation shows that ___.
Target: about 20 words
3 Cite Your Evidence
Write 2-3 sentences of evidence from the data table.

Your evidence should:
- Include specific numbers with units from the data table
- Show a comparison (highest vs. lowest, between conditions)
- Come from the investigation data, not background knowledge
Evidence is specific data from the investigation that supports your claim.

Strong evidence:
- Includes 2+ specific data points with numbers
- Comes from YOUR investigation data (not background knowledge)
- Distinguishes between primary data and background context
- Is directly relevant to your claim
Scoring Guidance — Step 3
Role: evidence
Target: ~40 words
Look for:
  • Use at least 2 specific numbers from the data table
  • Compare values: '...compared to...' or 'while...' or 'In contrast...'
  • Include units (cm, °C, mg/L, etc.)
Data Reference (Surface Temp (°C)) Asphalt pavement: 58Concrete sidewalk: 49Grass lawn: 32Urban forest / tree canopy: 24
Use at least 2 specific numbers from the data table
Compare values: '...compared to...' or 'while...' or 'In contrast...
Include units (cm, °C, mg/L, etc.)
Sentence Starters
The data table shows that when ___, ___.
Specifically, the measurement of ___ was ___.
Two data points that support my claim are ___ and ___.
Target: about 40 words
4 Write Your Reasoning
Write 3-4 sentences explaining WHY your evidence supports your claim.

Your reasoning MUST include:
- A named scientific principle (e.g., natural selection, Newton's third law, photosynthesis)
- An explanation of the MECHANISM: HOW does this principle cause your result?
- Language like "This demonstrates..." or "According to [principle]..."
Reasoning is the scientific explanation that connects your evidence to your claim.

Reasoning is NOT a repeat of your evidence. Reasoning MUST:
- Name a scientific principle or concept
- Explain the MECHANISM — HOW or WHY the principle causes the observed result
- Use language like "This demonstrates..." or "According to..."
Scoring Guidance — Step 4
Role: reasoning
Target: ~40 words
Look for:
  • Name the scientific principle: 'This demonstrates [concept]...'
  • Explain the mechanism: not just WHAT but HOW/WHY
  • Check: Did you actually explain the science? Or just restate the data?
Name the scientific principle: 'This demonstrates [concept]...
Explain the mechanism: not just WHAT but HOW/WHY
Check: Did you actually explain the science? Or just restate the data?
Sentence Starters
This supports my claim because the principle of ___ explains ___.
The scientific mechanism behind this is ___.
Therefore, when ___, ___ because ___.
Target: about 40 words
5 Write Your Rebuttal
Write 3-4 sentences for your rebuttal.

Your rebuttal should:
1. Name the most plausible alternative explanation for the data
2. Explain why someone might believe this alternative
3. Use evidence to explain why your claim is still better supported

Think: What is the strongest counter-argument someone could make? How does the data rule it out?
A rebuttal is what separates a strong scientific argument from a weak one.

Scientists must be honest about alternative explanations — and then explain why those alternatives are less supported by the evidence.

A strong rebuttal:
- Acknowledges a plausible alternative explanation (what a skeptic might say)
- Explains specifically WHY the evidence still supports your original claim
- Uses evidence to show why the alternative is weaker
- Does NOT just say "some people might disagree, but I'm right"

Weak rebuttal: "Some people might think that [alternative], but my claim is correct."
Strong rebuttal: "One alternative explanation is that [specific alternative], because [reason it seems plausible]. However, the data shows [specific data point] which rules this out because [scientific reasoning]."
Scoring Guidance — Step 5
Role: rebuttal
Target: ~50 words
Look for:
  • Start with: 'One alternative explanation is...' or 'A skeptic might argue that...'
  • Name the specific alternative: don't be vague
  • Use evidence to refute it: 'However, the data shows [specific numbers]...'
  • Explain WHY your data rules out the alternative
Start with: 'One alternative explanation is...' or 'A skeptic might argue that...
Name the specific alternative: don't be vague
Use evidence to refute it: 'However, the data shows [specific numbers]...
Explain WHY your data rules out the alternative
Sentence Starters
An alternative explanation is ___.
Some might argue ___; however, the data shows ___.
While ___ could explain this, the evidence more strongly indicates ___.
Target: about 50 words
6 Write Your Complete CERR Paragraph
Write your complete CERR paragraph (6-9 sentences).

Use your claim, evidence, reasoning, and rebuttal from previous steps.
Improve them as you write — aim for precision and flow.

Checklist before submitting:
- [ ] Claim: precise sentence answering the investigation question
- [ ] Evidence: 2+ specific data points with numbers
- [ ] Reasoning: named scientific principle + mechanism explanation
- [ ] Rebuttal: named alternative + evidence-based refutation
- [ ] Flow: transitions connect all four parts
Now assemble your entire argument into one polished paragraph.

Your scaffold boxes show what you've written — use those as your starting point and improve them.

A complete CERR paragraph for Grade 6-8:
- Starts with a precise claim (1 sentence)
- Provides 2+ pieces of evidence with specific data
- Explains reasoning with a named scientific principle and mechanism
- Acknowledges and substantively rebuts the best alternative explanation
- Flows with appropriate transitions
- Is 6-9 sentences

Transitions for CERR: "Furthermore," "This demonstrates," "However, a skeptic might argue," "The data refutes this because," "Therefore,"
Scoring Guidance — Step 6
Role: complete CERR paragraph
Target: ~130 words
Look for:
  • Claim → Evidence → Reasoning → Rebuttal is the standard CERR structure
  • Use transitions: 'This demonstrates...' → 'However, one alternative explanation...' → 'The data refutes this...'
  • Your rebuttal should feel like the strongest counter-argument you can imagine — then knock it down
Data Reference (Surface Temp (°C)) Asphalt pavement: 58Concrete sidewalk: 49Grass lawn: 32Urban forest / tree canopy: 24
Claim → Evidence → Reasoning → Rebuttal is the standard CERR structure
Use transitions: 'This demonstrates...' → 'However, one alternative explanation...' → 'The data refutes this...
Your rebuttal should feel like the strongest counter-argument you can imagine — then knock it down
Claim + Evidence + Reasoning + Rebuttal = Complete Paragraph
Sentence Starters
My claim is ___. The evidence shows ___. The principle of ___ explains this.
Some might argue ___; however, the data more strongly supports my claim because ___.
Target: about 130 words
Self-Check Rubric
Criteria ●●●●●
5 — Advanced
●●●●○
4 — Proficient
●●●○○
3 — Developing
●●○○○
2 — Emerging
●○○○○
1 — Beginning
Claim Clear, specific claim that directly answers the question Clear claim that answers the question Claim present but vague or partially answers question Claim unclear or off-topic No claim or unrelated
Evidence Multiple specific data points cited accurately Specific data cited accurately Some data referenced but vague Little or no data cited No evidence from data
Reasoning Explains WHY data supports claim using science concepts Explains connection between evidence and claim Some explanation but gaps in logic Weak or missing explanation No reasoning
Rebuttal Addresses alternative and explains why data disproves it Addresses alternative with evidence Mentions alternative but weak counter Does not address alternative No rebuttal

Before You Turn In

I completed the planning step
I wrote my claim
My claim is about 20 words
I wrote my evidence
My evidence is about 40 words
I wrote my reasoning
My reasoning is about 40 words
I wrote my rebuttal
My rebuttal is about 50 words
I wrote my complete CERR paragraph
My complete CERR paragraph is about 130 words
I re-read my writing and fixed any spelling or grammar mistakes
I am proud of this work

Reflection

What was the hardest part of this assignment? What would you do differently next time?

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