Reasoning and the CER Framework
Classroom, Science

Reasoning & the CER Framework

This post is the 4th post in the CER framework series. To read any of the previous posts in this series click on those below: 

The third part of the ClaimEvidenceReasoning (CER) framework is the “reasoning.” This step seems to elude students without specific guidance. It really is the critical step in knowing that students have made the connection between their investigation and the concepts they are learning. 

Reasoning and the CER Framework

The purpose of the reasoning is for students to be able to explain the why and how their evidence supports the claim. They should be drawing on the content they are learning or learned at this stage by providing a definition, rule or principle which may also include examples. This may take some in depth modeling and training.

For example, if you were having students make observations of different living things you might ask them to decide if a millipede is an insect? They would make their claim and find evidence using their observations. But to truly make their claim they would need to understand the characteristics or definition of what an insect is.This would require them to give you the definition of an insect and why the milliped does not fit with this model. This is the reasoning. 

Continue with the color coding process.  I use the color green for the reasoning. Whether posting stems on green paper or using a a green highlighter , this visual support will remind students of the importance of the reasoning. 

At a higher level you might be studying the conservation of energy. So in their activity they would state the law of the conservation of energy and how their lab did or did not demonstrate the law. So at this stage you get to see how well your students understand the concepts they are learning. 

As with claim or evidence students will need a strong model and coaching for how to incorporate reasoning. Additionally students will likely need collaborative activities that focus on clear reasoning, which could include a sorting game. 

To help guide your students you could ask them the following:

  • How do you know?
  • Why do you think this?

When students are ready to write their reasoning here a few sentence stems that will get them started and should be practiced verbally or through discussion before they begin the writing process. 


  • This happened because …
  • The reason the ____ is because…

Intermediate (or any primary examples)

  • The ____ showed _____ because…
  • An example of _____ is …
    (or any primary examples)


  • This means…
  • Due to _____ it is evident that…
  • There is little doubt that _____because…
    (or any primary or intermediate examples)

When students are preparing to write you could decide on the scaffolds needed by providing stems that you believe are the best for the type of claim they are supporting or have students discuss ahead of time with a partner or team before they begin writing. As long as you keep this process routine, then when it is time for them to do it on their own they will have a much better understanding on how to support their evidence with reasoning. 

To help you get started with some tools on the entire process, here are some great resources you can immediately put in the hands of your students and model with your class. 

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