What this assignment is really asking
Answer the question with a claim — a complete sentence that states your conclusion directly. The claim must do only one job: answer the focusing question. It should not include any explanation or reasoning. "The plant in the light condition grew taller" is a claim. "The plant grew taller because light provides energy for photosynthesis" is a claim with reasoning mixed in — split it.
Support the claim with specific evidence drawn from your experimental data or lab observations. Evidence is what you actually observed or measured — specific numbers, observations, or data points, not general statements. "The temperature increased" is too vague; "the temperature rose from 18°C to 34°C over 10 minutes" is evidence. Specific qualitative observations — a color change from clear to yellow, a substance dissolving completely, a leaf wilting — are also valid evidence when they are precisely described. Evidence is data only — no explanation belongs here.
Write a reasoning sentence for each piece of evidence. Reasoning explains why that specific evidence supports your claim by naming the science principle or concept that connects them. "This is because heat increases the rate of particle movement, which raises the temperature" is reasoning. "This shows my claim is correct" is not reasoning — it restates the relationship without explaining the science.
Use multiple evidence–reasoning pairs. Most teachers expect two or three rounds of evidence followed immediately by its reasoning. Each pair should present a distinct piece of data and a distinct scientific connection — not the same point restated twice.
These typically run 150–400 words — a paragraph or two. The goal is completeness, not length. Include all three components in every response and follow your teacher’s format expectations for whether they want labeled sections (Claim:, Evidence:, Reasoning:) or flowing prose.
First move
Write the claim before the explanation.
A CER response works only when each part has one job. Start by answering the focusing question in a complete sentence, then choose the data and science principle that prove it.
- Rewrite the focusing question as a direct answer.
- Pick two or three data points with numbers, units, or precise observations.
- Name the science principle that connects each data point to the claim.
What counts as evidence
CER evidence is specific data or observation. Reasoning is separate: it explains the science that makes the evidence support the claim.
Use this
If your teacher wants labeled CER sections, use labels. If they want paragraph form, keep the same jobs but write them as connected prose.
How to read a prompt like this
Use the CER format to explain which soil sample retained the most water, using data from the lab.
Question
which soil sample retained the most water
The claim should name one sample or rank the samples directly.
Evidence rule
using data from the lab
Use measured values, not guesses or background knowledge alone.
Hidden requirement
explain
Reasoning must connect the data to a science principle about water retention.
First action: Write the claim in one sentence, then pair each chosen data point with a reasoning sentence.
When teachers call it something else
Claim-evidence-reasoning
The full name of CER; each word names a required part of the response.
CER paragraph
Usually means the same structure in a shorter, paragraph-length format.
Have the exact prompt?
The guide explains the genre. The analyzer translates your actual assignment into a plan you can use.
Paste your exact promptHow to structure it
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Read the focusing question
Identify exactly what you are being asked to conclude. A question about which variable caused the most change needs a comparative claim, not just a description of what happened.
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See the difference
A stronger CER separates data from reasoning. Evidence tells what happened; reasoning explains why it proves the claim.
What teachers look for
Back to topA claim that answers the exact question in one complete sentence — and only the question. No explanation, no reasoning, no "because." One sentence, one job.
Specific, measurable evidence: actual data points, observations with units, or direct measurements from the experiment. Vague statements like "the results were different" are not evidence. Name exact values, quantities, or clearly observed outcomes.
Reasoning that names the science principle explicitly. The reasoning sentence should tell a reader — even one who has not seen your data — what concept from class explains why your evidence proves your claim.
Paired evidence–reasoning structure: each piece of evidence is immediately followed by its own reasoning sentence. Two or three pairs make a complete response.
Clean separation between the three parts. No part does another part’s job. This separation is exactly what your teacher is grading — it demonstrates that you understand the difference between observation and explanation.
Common mistakes to avoid
Back to topUsing vague evidence.
Looks like
"The temperature changed" gives no value, unit, or specific observation.
Fix
Use exact numbers, units, or clearly described observations from the lab.
Writing a claim that is too short or too broad.
Skipping the science principle.
Key terms
Back to top- Claim
- The direct, complete-sentence answer to the focusing question; contains no explanation or reasoning — one sentence, one job.
- Evidence
- Specific data, measurements, or observations from the experiment; no interpretation included.
- Reasoning
- The science principle or concept connecting the evidence to the claim; explains why the evidence proves the claim, not just that it does.
- Science principle
- The concept, law, or theory from class that provides the mechanism explaining the result — e.g., conservation of energy, natural selection, Newton's third law.
- Focusing question
- The specific question your CER response must answer — narrow enough to generate one testable claim. "How does photosynthesis work?" is a topic, not a focusing question. "Which light color produced the most plant growth in this experiment?" is a focusing question because it has one specific answer your evidence can prove.
- Data
- The measured or observed information from an experiment, such as numbers, units, or precise qualitative observations.
Frequently asked questions
Back to topWill BetterPaper write my CER for me?
No. It helps you separate your claim, evidence, and reasoning so each part is doing its correct job. You ran the experiment and you write the response in your own words. Your words, your grade.
What is the difference between evidence and reasoning?
Evidence is the specific data or observation from your experiment — the number, measurement, or outcome you recorded. Reasoning is the scientific explanation of why that data supports your claim. It names a concept, principle, or law from class. Evidence answers "what happened?"; reasoning answers "why does that prove the claim?"
How long should a CER response be?
Usually 150–400 words — a paragraph or two. The goal is completeness, not length. You need one claim, then two or three evidence–reasoning pairs. Once every part is present and each is doing only its own job, the response is complete. Do not pad it with extra sentences that restate the claim.
Do I need to write CER in labeled sections or as a paragraph?
Follow your teacher’s format. Some teachers want labeled sections (Claim:, Evidence:, Reasoning:) so each part is clearly visible. Others want the response written as connected prose. If your teacher did not specify, labeled sections are safer — they make it easy for your teacher to check that each component is present and doing its job.
What counts as evidence in an English or social studies CER?
In English class, evidence is a direct quote or a specific paraphrase from the text — a particular scene, line of dialogue, or described event. In social studies, evidence is a specific historical fact, event, date, or statistic. The rule is the same as in science: name the specific thing you found, not a general statement. "The story shows conflict" is not evidence; "In chapter three, Jonas discovers that the memories have been erased from the community" is evidence. Your reasoning sentence then explains why that specific detail proves your claim.
What is a prompt?
A prompt is the assignment your teacher gives you — the question or task you are being asked to respond to. It might be a paragraph, a few sentences, or a single question. The verbs in it (analyze, argue, explain, describe) tell you what kind of work is expected.
What is a rubric?
A rubric is the scoring guide your teacher uses to grade your work. It lists the criteria — things like thesis, evidence, organization, and mechanics — and describes what strong, adequate, and weak work looks like for each one. If your teacher provides one, read it before you write; it tells you exactly what earns points.