Claim-Evidence-Reasoning: How To Teach CER

Teaching claim-evidence-reasoning sounds simple on the surface. You get students to make a claim, support it, and explain their thinking. But in the classroom, the reasoning step can trip students up. 

Get a breakdown of how you can start teaching CER right away. You’ll get clear examples, grading tips, and ready-to-assign Newsela STEM activities that help students practice evidence-based explanations across science topics.

[What is claim-evidence-reasoning?](id-what)

Claim-evidence-reasoning (CER) is a framework students use to build explanations from evidence. In science, it helps them move beyond giving an answer and practice explaining how their data, observations, or research support that answer.

A CER response has three parts:

CER definitions

The three parts of claim-evidence-reasoning

Use these quick definitions to help students separate the answer, the proof, and the explanation.

1 Claim

Definition: The claim is the answer to the question or prompt.

Why it matters: A clear claim gives students one idea to prove with evidence.

2 Evidence

Definition: Evidence is the data, observation, fact, example, or research that supports the claim.

Why it matters: Strong evidence keeps students from relying on guesses or opinions.

3 Reasoning

Definition: Reasoning explains why the evidence supports the claim.

Why it matters: This is where students connect their evidence to a science concept, rule, or principle.

Student sentence frame: This evidence supports my claim because [science concept, rule, or principle].

The last part matters most. Students can collect strong evidence, but still write a weak explanation if they don’t fully understand or make the connection. CER gives them a structure for showing their thinking by stating what they think, showing what supports it, and explaining why the support makes sense.

Where did the CER framework come from?

Katherine L. McNeill and Joseph Krajcik helped develop and popularize the claim-evidence-reasoning framework. Their book, “Supporting Grade 5–8 Students in Constructing Explanations in Science: The Claim, Evidence, and Reasoning Framework for Talk and Writing,” breaks scientific explanation down into four areas:

• Claim
• Evidence
• Reasoning
• Rebuttal

This framework wasn’t designed to be just another writing template. It was created to help students do the work scientists do. 

What’s the difference between evidence and reasoning in CER?

Evidence is the “what” in CER. It’s the data, observations, fact, or example that supports the claim. Students might get their evidence from completing a lab, reading an article, or examining a data table or model. 

Reasoning is the “why.” It explains how the evidence supports the claim. This is where students connect their evidence to a science concept, rule, or principle. 

To help students understand the difference, try framing the concepts in this way:

• Evidence says: “Here’s what I noticed.”
• Reasoning says: “Here’s why that matters.”

[Why do students struggle with CER reasoning?](id-why)

Students usually understand that evidence supports a claim, but they may get tripped up explaining why. This is where CER responses can start strong and then fizzle out. And it makes sense.

Reasoning asks students to do several things at once. They have to:

• Understand the question.
• Choose relevant evidence.
• Remember the science principle that applies.
• Explain the connection in writing.

To help students master the trickiest part of CER, try treating reasoning as its own skill. Instead of asking students to “explain more,” ask them to name the science idea that makes the evidence matter.

[How do you teach claim-evidence-reasoning step by step?](id-how)

Teaching claim-evidence-reasoning is most effective when students can see each part of the thinking process before they have to write a full response. Start with the question, then help students form a clear claim. After that, help them select evidence that supports the claim and explain why it matters.

CER isn’t a formula, and every response doesn’t have to sound the same. But by using supports, students can build a habit of evidence-based thinking and have a framework that helps them convey that thinking in writing. 

1. Start with a question students can answer with evidence

A strong CER starts with a question students can actually investigate and analyze. If the question is too broad, students may write vague claims. If the question is too simple, they may not have anything meaningful to explain.

Try framing CER questions so students have to make sense of evidence, not just remember a fact. For example, asking “What happened during the chemical reaction?” may lead to a short answer. The solution fizzed. The gummy bear expanded. This handles the “what” but not the “why.”

A better question might be “How can you tell a chemical reaction happened?” This pushed students to make a claim, choose evidence, and explain how that evidence supports the claim.

2. Keep the claim short and clear

Once students understand the question, have them write a claim that directly answers it. The claim isn’t a full explanation. It’s a clear, defensible answer that students can support with evidence.

For early CER practice, claims should be simple. And they don’t have to start with “I think” or “I believe.” For example, if the question is “How can you tell a chemical reaction happened?” the claim can be as simple as “A chemical reaction happened.” The evidence and the reasoning will do the rest of the work.

3. Help students choose evidence that’s relevant and specific

After students write a claim, the next step is to choose the evidence that actually supports it. This is where they may need help sorting between evidence that’s just interesting and what’s useful.

Useful evidence is specific and points to data, observations, trends, or results. Plus, it connects directly to the claim. Have students answer two quick questions before they add evidence to their CER prompt:

1. Does this evidence connect directly to my claim?
2. Could someone else check or verify it?

By answering these two questions, students are more likely to cite real evidence rather than observations that “seem cool.”

4. Teach reasoning as the “why this evidence proves it” step

Reasoning is the part of CER where students explain the connection between the evidence and the claim. It answers the question: “Why does this evidence prove what I’m saying?”

This is also the step students are most likely to skip, forget, or struggle with. They may repeat evidence or write something like “this proves my claim” without explaining how. To help, ask students to name the science concept, rule, or principle that makes the evidence matter.

Try using a sentence frame like “This evidence supports my claim because…” Students can finish the sentence with the science idea rather than just another version of the evidence.

Tip: Model one complete CER before students write independently

Before students write their own CER responses, show them what the full process looks like from start to finish. Think aloud as you read the question, write a short claim, choose evidence, and explain how the evidence connects to the science data.

This is especially helpful for the reasoning step. Students need to hear the difference between “I found this evidence” and “This evidence supports my claim because…” 

As you model, pause to name the science concept, rule, or principle that makes the evidence matter. 

You can also model a weak CER and revise it with the class. Ask questions like whether the claim is clear, whether the evidence is specific, or whether the reasoning explains why the evidence proves the claim. This helps students see CER as a thinking process they can improve rather than a writing task they can rush through.

[How can you scaffold CER without turning it into a formula?](id-scaffold)

CER scaffolds can help clarify the thinking process, but they can also become a script students feel like they have to follow forever. The goal is to find a balance between providing support while also helping students understand that there are many ways to make a claim, support it with evidence, and explain the connection.

Start with supports that help students see the structure and lower the writing load so students can focus on the thinking process. Then, fade the supports as students get stronger. Instead of removing all the scaffolding at once, remove one layer at a time.

CER supports for multilingual learners and struggling writers

For multilingual learners and struggling writers, start by separating the thinking from the writing. Students may understand the science idea before they can explain it in a polished paragraph. Give them a way to build the CER orally, visually, or collaboratively before asking for a written response. The goal is to reduce the writing load without lowering the rigor.

When to use fade CER sentence frames

Sentence frames are useful when students are learning the CER structure, but they shouldn’t become a crutch for students when they’re writing responses. Once students can identify the claim, evidence, and reasoning in a model response, start fading the frames.

Do this in small steps to work students toward independent writing. Some students may need the frames longer than others do, especially when the science concept is new or the writing task is more complex.

Over time, fading support helps students use CER as a flexible thinking routine instead of a fill-in-the-blank paragraph. Research has found that students who received faded supports wrote stronger unscaffolded reasoning than students who received continuous detailed support.

Stop CER from being fill-in-the-blank writing

CER should give students structure, not a script. If every response sounds the same, students may be completing the format without doing the thinking. This can happen when sentence frames provide support for too long, or when students focus more on filling in the blanks than expressing their ideas.

To keep CER flexible, ask students to check the quality of each part, not just whether each part exists. It also helps to use CER in multiple formats. Students can use discussion, annotation, revision, and oral explanations before drafting. The more ways students practice the thought process, the less likely they are to treat CER as a fill-in-the-blank activity.

[How does CER fit into the science and STEM classroom?](id-support)

CER fits naturally into STEM because students explain phenomena, use evidence, and communicate reasoning. It also connects to NGSS practices such as engaging in argument from evidence, in which students support explanations with evidence and scientific reasoning.

How does CER support NGSS?

CER supports the Next Generation Science Standards (NGSS) by giving students a repeatable way to practice evidence-based science thinking. When students complete this framework, they’re doing the same kinds of work named in the NGSS Science and Engineering Practices, like constructing explanations, designing solutions, and engaging in argument from evidence.

Every NGSS-aligned task doesn’t need a CER component, but it does help gie students regular practice connecting evidence to scientific ideas, which can help them reach these standards more easily.

Is CER the same as the scientific method?

CER isn’t the same as the scientific method, but the two can work together to build skills. The scientific method helps students plan and carry out an investigation. CER helps students explain what the results mean.

The distinction matters because CER is more than just a lab conclusion format. Students can use CER after an experiment, but they can also use it to do other activities like:

• Analyze a graph.
• Respond to a science article.
• Compare models.
• Explain a phenomenon.
• Support conclusion during discussion.

[How should you grade CER responses?](id-grade)

Grading CER responses is easier when the rubric matches the structure students are learning. You don’t need a complicated rubric for every activity. The focus should keep grading manageable and give students clearer feedback.

If the goal is scientific thinking, don’t let grammar, spelling, or paragraph polish heavily influence the score. Those things may matter in the final draft, but CER practice should focus on helping students build stronger explanations first.

What does a CER rubric include?

A CER rubric should match the three parts students are practicing. Each part should describe what strong work looks like, not just whether the student included a sentence in the right spot.

The reasoning row is especially important. Students should explain how their evidence supports the claim by connecting it to a science concept, rule, or principle, and the rubric should reflect that. Keep this section focused on explanation quality, not just paragraph completion.

You can also add a short clarity category if students are writing a final response. While spelling and grammar matter, avoid making these elements or the formatting outweigh the CER thinking. For practice, it’s often enough to score the claim, evidence, and reasoning separately.

How many pieces of evidence should students include?

There’s no magic number students should include when adding evidence to their CER response. The right amount of evidence depends on the question, students’ grade level, the source material, and how much you expect them to write. 

For early CER practice, one strong piece of evidence is usually enough. That lets students focus on choosing evidence that’s relevant and explaining it clearly. As they get more comfortable, you can ask for two or more pieces of evidence so they can compare data points, combine observations, or support a more complex claim.

A helpful rule to remember is: Require enough evidence to prove the claim, but not so much that students skip the reasoning. If students continuously add evidence without explaining it, reduce the amount and focus the task on why the evidence matters.

How can I grade CER activities faster?

To grade CER activities faster, narrow the assignment focus. Instead of scoring every part of every response, choose one CER section to look at. For example, if today’s lesson goal is to understand evidence, score only whether students choose specific, relevant details. This makes feedback faster for you and clearer for students.

Eventually, you can build to grading all sections, after students have perfected each one individually.

You can also use quick codes instead of long comments. Try “C,” “E,” and “R” instead of spelling out the whole word. Then, add one short note about the next step. Students still get targeted feedback, but you don’t have to rewrite the same explanation on every response.

[Use Newsela STEM activities to practice claim-evidence-reasoning](id-newsel)

Once students understand the CER structure, they need repeated chances to practice with content that gives them something meaningful to explain.

Newsela STEM claim-evidence-reasoning activities can help students practice each step, and they’re ready-to-assign to cut down the prep time. Each one includes student instructions and a Newsela STEM article so students have a shared source to use as they build their CER responses.

Use these activities to introduce structure, review the CER framework, or give students targeted practice with evidence-based explanations.

Middle school CER activities

Middle school students often need repeated practice with all parts of CER. Newsela STEM has activities targeted to this specific grade band that give them opportunities to practice the skills with content they’re already learning in class. 

For this grade band, keep the focus on quality over length. A clear claim, one strong piece of evidence, and a well-explained reasoning sentence can be more useful than a longer response. 

High school CER activities

High school students can use CER to build more complex explanations from data, models, scientific principles, and article evidence. Newsela STEM’s activities for this grade band give students structured practice with CER questions across science focus areas.

At this level, ask students to choose evidence that shows a pattern, relationship, or trade-off. The reasoning should name the science concept that makes the evidence matter and explain why that evidence supports the claim.

How to use CER activities for introduction, review, or skills practice

You can use CER activities at different points in a unit, depending on what students need. At the start of a unit, a CER activity can introduce a question or phenomenon and help students activate background knowledge. During a unit, it can give students practice using new vocabulary, concepts, and evidence. At the end of a unit, it can work as a review task or short performance check.

[Claim-evidence-reasoning FAQs](id-faqs)

Even when students understand the basic CER structure, you may have questions about when to use it, how much support to give, and what counts as strong evidence.

Use these FAQs to make quick instructional decisions as you plan CER prompts, introduce the framework to younger students, or adapt claim-evidence-reasoning for different subjects and grade levels.

Help students build stronger CER responses with Newsela

CER gets easier when students have the right question, the right evidence, and enough support to explain their thinking clearly. Start small, model each part, and give students repeated chances to practice with content that actually gives them something to prove.

With Newsela, you can pair CER writing with engaging science articles and ready-to-assign activities that help students follow and remember the steps and hone their thinking. Sign up for Newsela to start your free trial of our subject products and start building stronger evidence-based writing routines in your classroom.