A classroom guide to teaching Claim, Evidence, Reasoning (CER), the three-part structure that turns a claim into a well-supported argument, with sentence frames and a grading approach for any subject.
Claim-evidence-reasoning (CER) is a three-part writing structure. Students state a claim, back it with a specific piece of evidence, then explain in their own words why that evidence proves the claim. In the guides we publish here, the last step causes the most trouble.
Students find real evidence but rarely explain why it counts. CER exists to fix exactly that gap.
A claim states the position, evidence supplies a specific fact that supports it, and reasoning explains why that fact proves the claim true.
The order matters as much as the parts. A claim with no evidence is an opinion. Evidence with no reasoning is a fact left standing next to an argument with nothing linking them.
Most points disappear at the reasoning step. It asks students to explain logic rather than simply locate a fact, and that is a harder skill to teach than finding a good quote.
The most common reasoning mistake is a sentence that just restates the evidence in different words. Rewriting the evidence is not reasoning, even when the new sentence is longer than the original.
The stronger version names a rule (what bravery actually means) and applies it to the specific choice in the evidence. That is the move reasoning has to make every time: state the rule, then show how the evidence fits it.
A blank page is the hardest part of any writing task, and a sentence frame turns "start from nothing" into "fill in this shape." Give your students two or three of these, and let them drop the frame once the pattern feels automatic.
Frames work as temporary scaffolding. Once a student can fill in a frame smoothly on three or four prompts, ask them to write the same response without the bracket labels, and check whether the claim, evidence, and reasoning are still all present.
A full CER response looks short on the page but does real analytical work in three sentences.
Prompt: Does the main character in the story grow over the course of the plot?
Claim: The main character grows because she starts the story afraid to speak up and ends it defending a classmate in front of the whole class.
Evidence: In chapter one, she stays silent when a teacher blames the wrong student for a mistake. In the final chapter, she corrects a teacher in front of the class to protect a friend.
Reasoning: Both moments put her in the same position, watching an adult get something wrong, but she reacts in opposite ways. The shift from silence to speaking up is the clearest sign the character has changed, since her behavior in the same type of situation now looks different.
Notice what the reasoning sentence does that a summary would not. It names the pattern, same situation, opposite reaction, then explains why that pattern proves growth. A plain summary would only restate what happened in each scene. For more finished paragraphs across biology, chemistry, physics, history and math, see the CER examples by subject.
CER started as a science-writing framework and still shows up there most often, but the same three parts apply to any subject that asks students to argue a position from evidence.
The National Science Teaching Association publishes classroom examples that treat CER as a repeated routine rather than a one-time worksheet. The same three-part structure gets used for a two-sentence exit ticket one day and a full lab report the next, so students build the habit through repetition instead of a single lesson.
Grade the three parts separately rather than the response as a whole, so a student can see exactly which piece is weak.
A simple three-point rubric works for most classrooms:
The rubric generator can turn those three criteria into a printable rubric in under a minute, with room to add subject-specific language for a lab report or a document-based question.
When you hand back a weak reasoning sentence, ask one question instead of rewriting it for the student: "why does that evidence prove your claim?" Students who can answer that question out loud usually just needed a nudge rather than a full re-teach of the skill.
A single CER paragraph is the building block. A full essay is several of them stacked under one thesis.
Sharpen the thesis first, since a vague thesis makes every paragraph below it harder to argue. The thesis statement generator gives students a few arguable starting claims to react to and narrow into their own position.
Once you have a sharpened thesis, each body paragraph becomes its own CER unit: a claim that supports the thesis, evidence specific to that claim, and reasoning that ties it back. The essay outline generator turns a sharpened thesis into paragraph-by-paragraph slots for exactly that structure, so students plan the argument before they draft a single sentence.
The first CER lesson should use a topic with almost no content load, so students can focus on the structure instead of the subject matter. A prompt like "Is a hot dog a sandwich?" or "Which season is best?" lets every student form a claim in seconds and spend the lesson practicing the harder skill: writing reasoning that actually explains the evidence.
Model one full example on the board before you let students write their own, and think aloud through the reasoning sentence as you write it. Students can usually write a claim and find evidence on their own by watching once. The reasoning step is the one they need to see a teacher build in real time, word by word, because it is the part textbooks rarely show worked out in full.
Move to the real content only after a low-stakes topic has gone well. A student who has never separated evidence from reasoning on an easy prompt will struggle to do it for the first time on a dense paragraph from a novel or a lab dataset, so the skill has to get built somewhere it costs nothing to get wrong. A printable CER graphic organizer with the guiding question in each box keeps that first attempt on the rails.
Four mistakes account for most of the weak CER responses a teacher sees across a stack of papers.
That single habit, built slowly, carries into every argument a student writes for the rest of the year. Start your class with one CER paragraph a week, on any subject, and grade only the reasoning sentence for the first month.
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CER stands for claim, evidence, reasoning, a three-part structure for arguing a position: state the claim, back it with a specific fact, then explain why that fact proves the claim. It started in science classrooms and now shows up in English, history, and math writing as well.
A single CER response is usually three to five sentences: one for the claim, one or two for the evidence, and one or two for the reasoning. A full essay stacks several CER paragraphs under one thesis, so length grows with the number of claims the essay needs to support.
CER works from upper elementary through high school, with the sentence frames doing more of the work for younger students and less for older ones. A third grader can use a fill-in-the-blank frame for a one-paragraph response, while a high schooler applies the same three-part logic without any scaffolding at all.
No. The five-paragraph essay is a whole-document structure, an intro, three body paragraphs, and a conclusion, while CER is the internal structure of a single paragraph or a single point within a larger essay. A five-paragraph essay written well usually has a CER structure inside each of its three body paragraphs.
"[Claim]. This is shown when [evidence]. This matters because [reasoning]." is a reliable starting frame for a first CER paragraph. Once students can fill it in smoothly across a few prompts, have them drop the bracket labels and write the same three parts in their own words.
There is no dedicated Claim, Evidence, Reasoning (CER) worksheet or downloadable PDF on this site. You can copy the sentence frames on this page directly into your own class materials. If you need a paper handout, print a lined or column layout from the blank worksheet templates tool and write those frames onto the sheet.
This guide is general information for educators, not legal advice. AI tools and school policies change quickly — verify specifics against your own school’s rules and the tools’ current documentation before acting.