CERC - Writing an Evidence Based Argument

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SWBAT to develop an evidence based argument using the CERC model.

Big Idea

Students use a claim, supporting evidence, logical reasoning, and a conclusion to write an evidence based argument.


5 minutes

The objective of this lesson is foster an environment where students are able to write an evidence based argument.  As a school site we have decided to use the CERC model as means to achieve this objective.  One of the primary reasons we have decided to use CERC (Claim, Evidence, Reasoning, Conclusion) is that it gives students structure, which is a primary need for our specific student population. Our student population is over 60% English Language Learners, which results in teachers needing to provide substantial scaffolding through modeling and ongoing practice.

The following is an explanation of the CERC model:

Claim is a statement about the solution to a problem or question. 

  • Answer to a question or problem.
  • Usually the easiest for students.

Evidence is a specific fact that supports a claim.

  • In science often referred to as data.
  • Must be appropriate (i.e. relevant to claim).
  • Must be sufficient. 
  • Not an opinion!

Reasoning explains why your evidence proves your claim to be true.

  • Explains how evidence supports the claim.
  • Often includes scientific principles.

Conclusion ties main points together.


Why take a C‐E‐R-C Approach?

• Students are more successful understanding what’s going on than with the generic term “conclusions”.

• This is how you make an argument or explanation convincing.

• This is what scientists do.

• This is the language of both the Common Core and the Next Generation Science Standards. 

Common Core Standards: Writing in History, Science, Technical Subjects

WHST.6‐8.1. Write arguments focused on discipline‐specific content.

• Introduce claim(s) about a topic or issue, acknowledge and distinguish the claim(s) from alternate or opposing claims, and organize the reasons and evidence logically.

• Support claim(s) with logical reasoning and relevant, accurate data and evidence that demonstrate an understanding of the topic or text, using credible sources.

• Use words, phrases, and clauses to create cohesion and clarify (transition words - see Guided practice section of lesson) the relationships among claim(s), counterclaims, reasons, and evidence.

• Establish and maintain a formal style.

• Provide a concluding statement or section that follows from and supports the argument presented. 

Next Generation Science Standards

Scientific and Engineering Practices

  1.  Asking questions (for science) and defining problems (for engineering) 
  2.  Developing and using models
  3.  Planning and carrying out investigations
  4.  Analyzing and interpreting data
  5.  Using mathematics and computational thinking
  6.  Constructing explanations (for science) and designing solutions (for engineering)
  7.  Engaging in argument from evidence
  8.  Obtaining, evaluating, and communicating information 

Why Writing Is Important?

  1. Writing helps students learn.
    • It forces students to organize their thoughts and find the relationships between ideas.
    • Writing holds ideas in place long enough for students to think about them.
    • Writing gets all students to participate.

     2. Writing helps you (as the teacher) spot misconceptions. 

Guided Instruction

20 minutes

In this section of lesson I introduce students to the CERC model by explaining why writing is such an important skill for scientists to develop.  It is important for students to understand that being a scientist is more than the stereotypical white lab coat, smoked filled beakers, and random explosions.  In reality much of a scientists time is spent making observations, creating a hypothesis, recording data, data analysis, and communicating their results in scientific journals.  As a result to be considered a true scientist one must be able to communicate their findings by making claims, including supporting evidence, and using logical reasoning.  

As mentioned before, CERC must be constantly modeled and practiced to gradually see improvement in students writing.  The following exercise is done as whole group where I model the use of the CERC Graphic Organizer and Transition Words.  

(I have attached CERC Writing Powerpoint from Santa Clara Office of Education which introduces the CERC model, use of the CERC Graphic Organizer and Transition Words to support students writing).

The first model exercise I use is Darwin's Finches CERC Practice.  This particular text deals with Darwin's Finches and their various beak adaptations to available food sources.  One of the reasons I like this exercise is that students are naturally drawn to animals and in addition this is a topic we wii revisit in our Evolution unit. 

 After reading the brief text on Darwin's Finches, students are required to make a claim to answer the following question:

In a well-organized paragraph, and based on the information in the text above, what will most likely happen to the finch population if the large seed plants become extinct? 

To model I provide students the following resources:

1)  CERC Writing - Introduces students to CER specifically noting that all 3 plus a conclusion are required when writing a scientific explanation.

2)  CERC Graphic Organizer - This tool allows students to visually see how all 4 areas of CERC are interrelated when writing a scientific explanation. It is important to take the time to point out each section of graphic organizer starting with question and proceeding to claim, evidence (source - if using multiple sources for evidence), reasoning, and conclusion (see CERC Writing Powerpoint).  The final section we complete is transition words (explained below).

3)  Transition Words - This tool provides students with words that create cohesion and clarify the relationships among claim(s), reasons, and evidence. Selected words are used to fill in corresponding boxes in CERC Graphic Organizer.

I have provided examples of a completed CERC graphic organizer, and sample student response with corresponding key for Evidence and Reasoning. In addition CERC Writing Powerpoint contains a sample paragraph response.  All three of these can be shown to students after group practice.

1)  Darwin's Finches CERC Graphic Organizer Example

2)  Darwin's Finches Key

Independent Practice

20 minutes

Now that students have navigated through the structured model using Darwin's Finches, they have independent practice using the CERC model.  I briefly review CERC and introduce Mr. Xavier's Murder Mystery through a Claim Evidence and Reasoning Presentation.

1)  Students are given the Claim and Evidence Murder Mystery case, which requires them to make a claim to answer the question, "What Happened to Mr. Xavier?" Was he murdered?

2) Students use CERC Graphic Organizer to organize their ideas.

3) Students responses are graded using Science Rubric Claim Evidence.

I have students work independently since I want them to individually practice this important skill.

Exit Ticket

10 minutes

As an exit ticket/homework assignment students are given the following assignment:

1. Use one of the sentence starters below to make a claim.

A) The greatest (choose one) football / hockey / baseball / basketball player is ________________________.

B) The best movie is ____________________________.

C) The greatest musical artist (solo or group) is ___________.

2. Write down at least 3 pieces of evidence that support your claim. (Data must be accurate.)


3. Provide reasoning that explains why you used the evidence you did to determine the "best".

4. On the next day

1. Students sit with all other students who chose the same category. (example: best movie)

2. Share their claim, evidence, and reasoning with the other students.

3. Have a debate.