Claim-Evidence-Reasoning In Science

How can you use the C-E-R format to engage students in arguing from evidence?

In the last post, we took a look at the difference between arguments and explanations.   Since Engaging In Argument is a key Science and Engineering Practice, we should be working to incorporate argumentation into our classroom. Argumentative essays are one way to provide students with the opportunity to participate in this Science and Engineering Practice.

This probably isn’t news, but the Claim-Evidence-Reasoning approach is one way to help students form written arguments.  All too often, students provide claims without supporting their claims with evidence.  Likewise, when evidence is provided, students often fail to provide the reasoning that connects the evidence to the claim.  Engaging in argument from evidence expects students to not just provide evidence but provide the reasoning that links all three elements. 

So how can we help students achieve this?


Starting With The Claim

First, Claim-Evidence-Reasoning (CER) tasks should start with an open-ended question.  It is important to frame the question in a way that forces students to take a stand or support a single argument.  “What are the characteristics of living things?” is not an appropriate question for an argumentative essay.  “Is a seed a living thing?” is open to interpretation.  Students must argue their viewpoint based on evidence collected and understandings developed.  Crafting your question is vital to providing the framework for students to engage in argumentation.

In a CER essay, students would answer the question with their claim.  It is a simple, straightforward response to the question.  However, claims must be based on evidence, so it is important to provide students with the opportunity to collect and make sense of their evidence before crafting a claim of any sort.  Too often, students construct a claim and then search for the evidence to support it.  While on occasion this has served science well (continental drift, for example), typical practice expects scientists to objectively examine evidence before drawing conclusions.  We should teach our students to do the same.


Incorporating Evidence

The evidence students collect and use in their CER essays can take many forms.  It can be drawn from student investigations (labs, experiments, simulations, or simple observations) or from scientific texts or videos. Oftentimes, when writing their Evidence section, students will make broad statements without providing details.  It is important that we encourage them to provide the details necessary to sufficiently support their claim.  

On the other hand, students may struggle with recognizing appropriate evidence — evidence relevant to their claim.  Providing unrelated evidence can “muddle” arguments, so it is important to filter their work to highlight only the most important information. Graphic organizers can really help with this process.  Students can review their work from their notebooks or worksheets, highlighting or starring what they feel is most relevant.  Then, before writing begins, students can transfer that information to a single graphic organizer, so that all of the relevant information is right at hand.  Seeing it all together can also help students improve or refine their own arguments.


Scaffolding The Process

To guide students through this process, you may want to ask questions like: Do you have enough information to support your claim? Is there other evidence that supports that claim? Is there evidence that suggests another claim might be more appropriate? What do you think about the quality of the evidence that supports your claim? 

Additionally, other scaffolds you can use with students as they collect their evidence include:

  • – providing key vocabulary to focus on
  • jigsaw evidence collection (all students engage in all tasks, but groups focus on pulling appropriate evidence from each task)
  • note taking requirements (only 4-5 words per note; NO sentences)

Establishing Reasoning

The Reasoning section of your CER is where students provide the why — the meaning of it all.  It is where students justify how the evidence supports the claim.  You can help students connect their evidence to their claim by using an organizer to match up the main idea (or point they are trying to make) with each piece of evidence, answering questions like “How do you know that? What evidence supports that?”  Then, you can use additional questions to connect the evidence to the claim, such as “Why is this important to the claim? What does it mean? Why does your evidence answer the question? What scientific ideas or principles helped you make sense of your evidence/data?”

You can also provide students transition words to help connect their ideas: in addition, although, first, however, in conclusion, etc. 

Writing argumentative essays – whether you use the CER format or any other – is a challenge for many students, and each element should be explicitly taught and practiced.  There are ways you can help students understand and develop this skill, but we will get into that in a future post!


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