Equip ELA and humanities students with essential argumentative writing skills using this Claim-Evidence-Reasoning (CER) lesson plan. Teach learners how to define claims, locate the strongest textual evidence, and construct compelling explanations. Includes engaging activities, modeling steps, and differentiation ideas for scaffolding.

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The Evidence Detective: Proving Your Point

Materials Needed

Printed or digital copies of two short, engaging source texts (Texts A and B). (Example Text A: A fun fact sheet about a specific animal, like the giant squid or a specific type of robot.)
Highlighters or digital annotation tools.
Notebooks or blank paper/digital document for writing.
Pencils or pens.

Learning Objectives (The Goal)

By the end of this lesson, you will be able to:

Define the difference between a "claim" (an argument) and "textual evidence" (the proof).
Search a text efficiently to find the most relevant sentences that support a specific claim.
Construct a clear, well-supported argument using the Claim-Evidence-Reasoning (CER) structure.

Lesson Introduction: Tell Them What You'll Teach

The Hook: The Case of the Missing Proof

Educator Prompt: Imagine you are watching a TV detective show, and the detective declares, "I know who the thief is!" If they don't have any evidence—like fingerprints, security footage, or eyewitness reports—will anyone believe them? Probably not!

The same is true for writing. When you make an argument or a general statement (your Claim), you need solid proof (your Evidence) from the text to make people believe you. Today, we become evidence detectives!

Success Criteria

You will know you have mastered this lesson if you can:

State a claim.
Identify at least two pieces of text evidence (direct quotes or paraphrases) that support the claim.
Explain how the evidence proves the claim.

Lesson Body: Teach It

Phase 1: I Do (Modeling the Skill) – Introducing CER

Step 1: Define Key Terms

Claim (C): This is your argument, statement, or the point you are trying to prove. (Example: The ocean is a dangerous place.)
Evidence (E): Specific details, facts, quotes, statistics, or examples taken directly from the source text that support your claim. (Example: "Sharks are responsible for 10 reported attacks each year.")
Reasoning (R): Your explanation of *why* and *how* the evidence proves the claim. This links the two together. (Example: The fact that dangerous predators like sharks attack humans proves the general statement that the ocean environment can be perilous.)

Step 2: Educator Modeling (Using Text A)

Educator Action: Distribute or display Text A (e.g., the fun fact sheet about the giant squid).

Modeling Example:

State a Claim: "I claim that the Giant Squid is an impressive but rarely seen creature." (Write this down.)
Search for Evidence: I will scan the text looking for facts about its size and how often it’s observed. I find this sentence: "The giant squid can grow up to 43 feet long, making it one of the largest invertebrates on Earth." (Highlight this.) I also find: "Most knowledge about the squid comes from dead specimens washed ashore, as live sightings are extremely rare." (Highlight this.)
Provide Reasoning: I explain my thinking. The first piece of evidence proves it is impressive because of its huge size. The second piece of evidence proves it is rarely seen because scientists usually only find them after they have died. Both pieces work together to support my claim.

Phase 2: We Do (Guided Practice) – Selecting the Best Proof

Activity: Evidence Scavenger Hunt (Using Text A)

Transition: Now let's try finding the evidence together. You will practice identifying strong evidence versus weak evidence.

New Claim: "The giant squid faces many survival challenges in its deep-sea environment."

Educator Prompt (A): Look back at Text A. Does the sentence, "The squid's eyes are the size of basketballs," support this claim?

(Learners should answer No. Discussion: While interesting, huge eyes don't relate to 'survival challenges.')

Educator Prompt (B): What about the sentence, "The only known predator large enough to regularly consume the giant squid is the massive sperm whale"?

(Learners should answer Yes. Discussion: Having a massive predator is definitely a survival challenge.)

We Do Practice Writing

Using the strong evidence identified in Prompt B, learners draft a quick CER paragraph guided by the educator.

C: The giant squid faces many survival challenges in its deep-sea environment.
E: The text states, "The only known predator large enough to regularly consume the giant squid is the massive sperm whale."
R: This proves the claim because having a massive predator that actively hunts them is a significant and constant threat to their survival, showing the difficulty of life in the deep ocean.

Formative Assessment Check: Ask learners to explain the difference between the Claim and the Reasoning in their own words. (Claim = What I think; Reasoning = Why the evidence matters.)

Phase 3: You Do (Independent Application) – The Text Detective

Activity: The Ultimate Proof (Using Text B)

Transition: It’s time to apply the CER structure completely on your own using a new text.

Instructions:

Read Text B (e.g., a short article about why certain planets were reclassified).
Analyze the following general statement (Claim): "The classification of planets in our solar system has changed significantly over time due to new scientific understanding."
Find two distinct pieces of evidence (specific sentences or facts) in Text B that strongly support this claim. Highlight them.
On your paper, write one cohesive paragraph that uses the CER structure to prove the claim. Make sure your Reasoning clearly connects your evidence to the claim.

Success Check: Did you use quotation marks if you quoted directly? Did you explain why the piece of evidence you chose actually matters?

Lesson Conclusion: Tell Them What You Taught

Recap and Review

Educator Prompt: Today we learned how to become evidence detectives! What are the three parts of a strong, written argument?

(Expected answers: Claim, Evidence, Reasoning.)

Real-World Application: Why is this skill important outside of school? (Discussion: It helps you win debates, write convincing emails, or prove why you deserve that extra screen time by showing evidence of completing chores.)

Summative Assessment: Peer/Self-Review

Learners exchange their CER paragraphs (or read them aloud to the educator/group).

Feedback Checklist: Use the following questions to evaluate the paragraph:

Is the Claim clearly stated? (Y/N)
Is the Evidence specific and taken directly from Text B? (Y/N)
Is the Reasoning strong? Does it explain *how* the evidence proves the claim? (Y/N)

The goal is a paragraph that earns "Yes" for all three points.

Differentiation and Adaptability

Scaffolding (For Struggling Learners)

Highlighting Support: Pre-highlight three possible sentences in Text B and have the learner choose the two strongest pieces of evidence.
Sentence Starters: Provide sentence starters for the Reasoning section: "This detail proves the claim because..." or "Since the text explains [evidence], it demonstrates that [claim] is true because..."
Shorter Text: Use Text A again for the independent practice, keeping the content familiar.

Extension (For Advanced Learners)

Counterclaim Challenge: Provide a claim that is not supported by Text B. Challenge the learner to identify a counterclaim (the opposite argument) and find evidence in the text to support the counterclaim instead.
Evidence Evaluation: Require the learner to select three pieces of evidence and then rank them from strongest to weakest, justifying their ranking in their Reasoning section.
Source Synthesis: Give a third, very short Text C, and ask the learner to pull evidence from both Text B and Text C to support the same claim, requiring synthesis across sources.

CER Strategy Lesson: How to Support Claims with Textual Evidence (Claim-Evidence-Reasoning)