Claim, Evidence, Reasoning: Guide with examples and rubric
Use this guide to teach CER, show labeled examples, and grade responses with a rubric. Built for K-12 science teachers.
What Claim, Evidence, Reasoning is
Claim, Evidence, Reasoning (CER) is a three-part framework for writing scientific explanations. Students use it to answer open-ended questions with data instead of opinion, a practice emphasized in the Next Generation Science Standards (NGSS).
Claim
A clear, one-sentence answer to the question being investigated. A claim is not a guess and it is not the whole explanation. It is the conclusion the data points to.
Evidence
The specific, scientific data that supports the claim. Good evidence is sufficient and relevant. It can be quantitative (measurements) or qualitative (observations), and it usually comes from a lab, a reading, or a data set.
Reasoning
The link between the evidence and the claim. Reasoning explains why the evidence supports the claim by naming the underlying scientific principle.
How students should write CER
A CER paragraph is usually a short paragraph with at least four sentences, depending on the question and grade level.
- Step 1
Restate the question
Turn the prompt into a topic sentence so the answer has context.
- Step 2
Make the claim
Write one sentence that directly answers the question.
- Step 3
Give the evidence
Cite the specific data that supports the claim. Name the measurement or observation, not a vague summary.
- Step 4
Explain the reasoning
State the scientific principle and connect the evidence to the claim.
- Step 5
Check it
Read the paragraph and confirm the evidence is sufficient and the reasoning names a concept, not just a restatement.
Labeled CER examples
The fastest way to teach CER is to show labeled examples, then ask students to find each part themselves.
Worked example
Is air matter?
Air is matter.
When we pumped more air into the basketball, its mass increased each time we measured it on the balance.
Matter is anything that has mass and takes up space. Because adding air increased the measured mass, air must be matter.
Hint: Ask students to highlight the claim, underline the evidence, and circle the reasoning in different colors, then write their own CER for a new question.
How to grade using CER rubric
A CER rubric scores claim, evidence, and reasoning separately, often on a 0-3 scale, so students see where they're strong and where they need to improve. Use the same rubric across classes and co-teachers, and calibrate on a few samples before grading everything.
Claim
- 0 Missing:
- No claim, or claim does not answer the question
- 1 Beginning:
- Claim is vague or partially correct
- 2 Developing:
- Claim answers the question
- 3 Proficient:
- Claim is accurate, clear, and complete
Evidence
- 0 Missing:
- No evidence
- 1 Beginning:
- Evidence is irrelevant or incorrect
- 2 Developing:
- Some appropriate evidence, but not sufficient
- 3 Proficient:
- Sufficient, relevant, accurate data
Reasoning
- 0 Missing:
- No reasoning
- 1 Beginning:
- Restates evidence without a principle
- 2 Developing:
- Connects evidence to claim, principle unclear
- 3 Proficient:
- Connects evidence to claim using a correct scientific principle
CoGrader uses your CER rubric to score claim, evidence, and reasoning automatically, so you review instead of hand-scoring every response.
Grade CER Essays faster with CoGrader
CoGrader applies your CER rubric, drafts feedback, and sends it to you for review.
Pick a rubric from our library, or let CoGrader detect the right one from the essay.
- 1
Bring your rubric
Set up your CER rubric in CoGrader or tweak a template.
- 2
Import responses
Paste CER work or pull assignments from your LMS.
- 3
Let CoGrader score
It scores each response and drafts feedback by claim, evidence, and reasoning.
- 4
Review and send
You edit scores and comments, then return them to students.
Meet your CER grading tool
Grading CER is one assignment. CoGrader helps with your whole writing workload, while keeping you in control of every grade.
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Integrations that CoGrader supports
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You get the first draft, so you can focus on the comments that actually move the needle.
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Frequently Asked Questions
Claim, Evidence, Reasoning, answered.
What does CER stand for in science?
CER stands for Claim, Evidence, Reasoning. It is a framework for writing scientific explanations. The claim answers the question, the evidence is the data that supports the claim, and the reasoning explains why that evidence supports the claim using a scientific principle.
What is a CER paragraph?
A CER paragraph is a short scientific explanation, usually three to six sentences, that states a claim, backs it with specific evidence, and explains the reasoning that links the evidence to the claim. It is used to answer open-ended science questions with data instead of opinion.
What is reasoning in a CER?
Reasoning is the part of a CER that explains why the evidence supports the claim. Strong reasoning names the underlying scientific principle and connects it to the evidence, rather than simply restating the data. It is usually the most difficult part for students to write well.
How long should a CER be?
For most classroom questions, a single CER paragraph of three to six sentences is enough: one sentence for the claim, one or two for the evidence, and one or two for the reasoning. Lab conclusions or higher grade levels may call for a longer multi-paragraph response.
What is an example of CER?
Claim: Air is matter. Evidence: The basketball gained mass each time we pumped in more air. Reasoning: Matter is anything that has mass and takes up space, so because added air increased the mass, air is matter.
How do you grade a CER?
Use a rubric that scores claim, evidence, and reasoning separately, often on a 0 to 3 scale, and apply the same rubric across all classes. To grade a full set faster, a tool like CoGrader can apply your rubric inside Canvas or Google Classroom and draft feedback for you to review and edit. CoGrader also has dedicated essay graders for AP, state tests, and other rubrics.
Can CoGrader grade CER responses?
Yes. CoGrader's AI essay grader applies your CER rubric to student responses in Canvas or Google Classroom, scoring claim, evidence, and reasoning and drafting feedback for each one. You review and adjust every score before it reaches a student, so you keep final say.
Where can I learn more about teaching CER?
The CER framework is well documented for K-12 science. For background and classroom strategies, see Edutopia's overview of the CER framework in the science classroom, the NSTA elementary CER rubric, and the argumentation practices in the Next Generation Science Standards.
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