CER 101

Curious about CER or how to start incorporating it in class? Propello's got it covered!

When it comes to science, we think about the natural world. Investigations. And yes…experiments! It’s all about observations, seeing what happens, figuring out why, and communication.  


Wait, communication in science class? Absolutely! Scientists communicate all the time. They communicate what they want to learn about a scientific phenomena, what they think will happen, and after the experiment or investigation, what they learned. In science class, it’s important for students to be able to do the same.  And that’s where CER comes in. 

What is CER? 


An acronym for Claim-Evidence-Reasoning, CER is a powerful classroom tool that enables students to communicate their findings, observations, hypotheses and ideas effectively. Here’s how it works: 


Claim (C): This is a student's answer to a question or prompt. For example, a student may be asked “Why is it colder in the winter the further north you go?” 

The student may answer: “Because you are getting closer to the Earth’s pole.

This is the claim. 


Evidence (E): This is the “proof” the student has to justify the claim. In the beginning of a unit, this evidence could be based on background knowledge or anecdotal evidence (“All the places close to the North Pole have more snow,”, or “There is less snow the further south you are.”) 

After the unit of study, the answers may incorporate more scientific data and evidence (“Because of the Earth’s tilt and revolution around the sun.”). 


The key with evidence, be it anecdotal or based in data, is that it must be relevant, valid, and reliable. 


Reasoning (R ): This is how the student connects the evidence to the claim, in other words, how they know they’re correct. 


In the beginning, this could be an anecdotal justification based on personal observations (“It doesn’t snow in the summer up north,”). After studying the topic,  it can be based on the scientific knowledge they’ve gained (“The poles receive less of the sun’s energy during the winter because of the angle of the Earth’s axis, therefore there is less heat.”).

It can also be a combination of the two (“It’s much colder, and snows more in the winter. This is because the poles receive less of the sun’s energy due to the angle of Earth’s axis as it revolves around the sun. Therefore, it’s colder and you get more snow.”). 


The key is that the reasoning must show how the evidence supports the claim.


CER in the Classroom

Even though CER is a powerful tool for communicating ideas, evidence and justification, it’s not something many students are used to working with. You can begin by explaining CER to your students, and using examples to illustrate how to write a claim, support it with evidence, and provide reasoning to justify it, as we did above. 


Practice with Examples: Once students are familiar with the framework, give them examples of prompts so they can practice with it. For instance, you can provide a graph or chart and ask them to make a claim, support it with evidence, and provide reasoning.

Alternatively, you can ask them to look at an experiment and use the CER framework to provide a conclusion. Allow students to work through examples together and encourage dialogue as well as quick feedback.


Using CER to Practice Academic Writing and Speaking: Science is not the only subject that requires critical thinking and structured arguments, especially when it comes to academic communication.

By using the CER framework in science class, you are also teaching your students academic writing and speaking. Students are learning how to justify arguments, think critically, and communicate in language and tone other than casual conversation. 


These skills can benefit them in other academic subjects as well as in professional fields when they become adults. By giving them solid examples, explaining its functionality, and giving them opportunities to practice, you are actively helping them prepare for higher education and future careers.

In Summary


The CER framework is a powerful tool that enables students to develop critical thinking, reasoning, investigative skills, and structured writing. As a science teacher, you can help your students develop and practice these essential skills by introducing them to, practicing with examples, and using structured templates (like this one provided with your Propello account).


By doing so, you will empower your students to not only learn science, but think critically and articulate their thoughts effectively in ways that will help them succeed in other subjects and in their future professional careers.