Using Claim-Evidence-Reasoning to Support Student Ideas in Science

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SWBAT effectively demonstrate their ability to support a claim with appropriate evidence and reasoning

Big Idea

6th grade students have lots of ideas and generally know the importance of evidence; however, they often lack the structure to effectively communicate and make connections. Using Claim-Evidence-Reasoning helps establish this important skill!

Do Now

5 minutes

I begin with a Do Now that most students can relate to from their exposure to television shows, etc.

What would happen if a lawyer didn't have evidence to support what they were saying in a given court case?  What does the lawyer have to do with the evidence to make her point?

I write this Do Now question on the board to get my kids thinking about the importance of evidence in life and in science.   Students generally respond with the following statements (paraphrased):

  • The judge won't believe her if she doesn't have proof or evidence. 
  • The lawyer's ideas wouldn't be taken seriously.
  • She will lose the court case.

I then reiterate that they are correct and they just having evidence isn't enough--we have to explain (reason) how the evidence supports what we are trying to explain.

In class, we are going to learn about Claim-Evidence-Reasoning as a structure to help us to correctly explain how we know what we know.  

The Basics of Claim-Evidence-Reasoning

The image below does a good job of highlighting the various parts of Claim-Evidence-Reasoning (C-E-R), and the concrete nature of these guiding questions gives my students a solid structure to present their explanations of scientific phenomena.  


Picture source: Edutopia

In the Egg Mystery lessons students were guided through the process of collecting information and it is now time to make sense of it.  This is an exceptionally difficult skill that has induced a lot of anxiety in my students over the years.  Thus, I have started using C-E-R to help guide them through the process of making sense of their data.

According to the C-E-R model, an explanation consists of:

  • A Claim that answers the question
  • Evidence from students' data (in this case, what they collected while researching on day 2)
  • Reasoning that involves a "rule" or scientific principle that describes why the evidence supports the claim.  This is where students often struggle so modeling my expectations and assisting them to fine tune this skill continues throughout the year.


My classroom has evolved into a much more inquiry-driven, co-creative atmosphere.  In that, my role has evolved from a direct instructor to a facilitator of learning.  I have found that providing clear structures in class help with student focus and their ability to make connections.  C-E-R also promotes facilitating discussions, seeing the big picture, questioning alternative conceptions, encouraging collaboration, and, most importantly, shifts the focus to student conceptual understanding by using evidence to support their ideas (Reference: The Best Teacher in You).  In terms of NGSS - multiple science and engineering practices are developed in this activity, including argumentation and forming explanations from evidence.

Modeling Claim-Evidence-Reasoning For Students

8 minutes

Modeling C-E-R for my students is an important first step, requiring direct instruction. I begin by asking a fairly basic question, "Does air have mass?"  

I've selected this topic because I want to make C-E-R easy to comprehend and practice. Air having mass is a relatively easy concept to support with evidence and reasoning.

Remember: The ultimate goal is to get my students to explain how the egg got into the flask, but I must first show them how to make sense of their data before they can tackle that rather daunting task.

I project this on the board as I talk about it with the class, modeling my thought process as I proceed:

Question: Does air have mass?

Claim: Air is matter and therefore has mass and takes up space.

Evidence: In the second link that we used in class on day 2, we found that the mass of the basketball increased from 571 g to 576 g after air was pumped into it.  Also, when air was pumped into the basketball it got bigger.  We also observed that the air canister started with a mass of 135 g and then, after air was let out of the canister, it had a mass of 132 g.

Interject meaning into the evidence portion--State: "Do you notice that I didn't explain anything in this section.  I am simply recording the facts from the research that we did yesterday.  Just like an attorney, scientists must first gather their evidence before they can make sense of what it means or explain how it supports their ideas.  We will explain what our evidence means in the next section."

Proceed to read reasoning section to class.

Reasoning: The data show that air has mass, one of the characteristics of matter.  If air didn't have mass then the mass of the basketball and air canister would not have changed when air was added or removed.  Also, since the basketball got larger when air was pumped into it, we know that air takes up space, as well.  If air didn't take up space then the basketball would have remained the same shape.  This supports our claim that air has mass and volume.  

Practice 7--Engaging in argument from evidence.  

Clarify the importance of using evidence to support our explanations in science--State: "If I just say here is my evidence but don't explain how it supports my claim, then no one in the science community is going to value my claims.  I must explain how the evidence supports my claim.  This is similar to an attorney who is trying to convict a criminal.   Just as an attorney needs to collect evidence and express to the judge how it connects to their claim(s) that the defendant committed the crime, scientists must do the same thing.  If we as scientists just present a bunch of evidence but don't explain/reason how it relates to our claims, then we are not taking full advantage of explaining our findings!  Using CER for the remainder of our scientific careers will help establish cause and effect relationships with evidence that support our claims.  In this class, we will always clearly explain our understanding using C-E-R.

I give students this sheet as a reference for future C-E-R activities performed this year.  They staple the sheet into their science notebooks.

Students Practice Claim-Evidence-Reasoning With Teacher Guidance

10 minutes

Now that I have modeled C-E-R for my students, I want them to try it with a partner before I just let them try it within their larger groups.  This technique allows me to formatively assess each students' ability to use CER, enabling me to remediate or reteach as needed.  

I first develop a question and students can then perform C-E-R for that question.  

Important Note: Typically students generate questions and then perform investigations on their own.  I decided that guiding them with predetermined links from which to gather their research was advantageous in this situation.  C-E-R and evidence-based writing is a relatively new skill and I didn't want to overwhelm them too much by adding other responsibilities.  Through guidance throughout the rest of the year, I hope that students will be able to generate their own questions, find and determine what relevant research looks like and then effectively reason how their evidence supports their claims.

  • I present the following question to students: Does temperature affect air?


Students then work with the partner to develop a claim, supported by evidence and reasoning.

I circulate around the room and remind struggling students that we looked at a website where they could manipulate the temperature and view how it affected molecules.

The video clip below depicts argumentation between group members and how I helped guide their inquiry.

I then have students share their C-E-R and we analyze the effectiveness of their reasoning.

Groups Practice Using C-E-R

35 minutes

Before groups begin working together to complete the C-E-R, I present several questions that will guide them through the process.


  • Does air temperature affect hot air balloons?
  • How do ignited matches affect air?
  • How does heat affect air pressure?
  • Why did the matches go out during the egg demonstration, even though they weren't done burning?


I want my students to develop good C-E-R skills so I scaffold the difficulty of the questions from relatively straight forward to more challenging.  I allow my students to revisit the online simulations and sites if they need to gather more evidence.  I use this as a teaching moment to point out the importance of being thorough and recording evidence, even if they think it doesn't relate to what they are doing.

I then lead a class discussion/review of group C-E-R responses.  We then critique each others work and determine other evidence that may strengthen our explanations and discuss where/how we would find it.

Homework: Tying It All Together--How Did That Egg Get In There?!

By now my students are feeling comfortable using CER and want to delve into explaining how the egg got into the flask.  I ask them to do the following:

1) They have to create a one-page description on a separate sheet of paper, not in their science notebooks that explains their ideas of how the egg got into the flask.  I then collect, assess the use of CER and return with feedback.  This is then stapled into their science notebook.

2) Any claim that they make about the sequence of events needs to be evidence-based and logically reasoned.  This can be in the form of a diagram with captions.  Claims, Evidence and Reasoning must be identified with a 'C', 'E' and 'R' respectively.

Tomorrow we will have a 15 minute peer sharing session where students listen to other students' explanations of the egg mystery.  

Students then create a poster (day 3) that illustrates their C-E-R to explain how the egg got into the flask.  This activity is much more about their ability to support their claims with evidence than it is about getting their explanation perfect.  I do not tell them how the egg got into the flask, if they are on the right track--they will have to figure it out as we go through the course of this year.  This activity is about using evidence and reasoning to establish a viable explanation, not getting the correct answer!

This video show how students were assessed on the ability to use C-E-R to effectively communicate their ideas (SP8).  Students were assessed using this rubric.

Scientific models are never complete and neither are theirs, but they can always continuing inquiring about and testing ideas!