What Is A CER In Science? Student Examples

A CER in science stands for Claim, Evidence, and Reasoning. It is a framework for making scientific explanations in the science classroom. The Claim is the reponse to a question that is asked or the response to a phenomena. Evidence is the data that you gather or information that you find relative to the claim. The Reasoning is the logical connection between the Evidence and the Claim.

A CER should not be a lab report or several pages in length. It should include only 3 sections, the Claim, Evidence, and Reasoning.

Let’s take a look at each one with some students samples too.

How To Write The Claim Of The CER

The claim should be no longer than one sentence and it should address a question or should be in response to a phenomena.

Don’t worry about whether or not the claim is accurate, it doesn’t have to be.

The claim is simply an answer to a question that students will later gather evidence for that supports or doesn’t support their claim.

Let’s look at an example that I have used in my science class as a phenomena that leads to students creating their Claim.

Example: Ask your students a question like this: What will happen if I add 1 ice cube to 50 mL of boiling water? (don’t do a demonstration of this, let your students do it so they can gather evidence/data)

We typically review the claims to make sure we are able to collect evidence that addresses the claim.

For this investigations students typcially wrote down one of the following two claims.

 Note: not all students chose the same claim, that is okay.

Claim 1: Adding 1 ice cube to 50 mL of water will stop the water from boiling.

or

Claim 2: Adding 1 ice cube to 50 mL of water will not stop the water from boiling.

At this point we were ready to collect some evidence/data regarding the claim so they can decide whether or not their claim is accurate based on data evidence.

How To Gather Evidence For A CER

Gathering the evidence is the part student like the most because they are actually doing something and recording that in order to determine if their Claim is accurate or not.

Allow your students to make observations and to record them without worrying whether or not their claim is “right” or “wrong”.

The point is not to be right/wrong, the point is to be able to address the claim with specific evidence/data.

Sometimes they will collect their own evidence (lab or experiment) or they may just research information using the internet.  

In the example below I had my 8^th grade students submit pictures and a data table.

For this example I provided students with everything they needed to test the claim.

I had hot plates (these are great ones on Amazon), ice cubes from the teacher lounge, thermometers (like these), water, and beakers.

Collecting Their Evidence: Students filled their beakers with 50 mL of water from the faucets in my classroom and used the hot plates to get the water to a full boil.

During this they also measured the temperature using the thermometer.

When the thermometer stopped at 100 degrees Celsius or 212 degrees Fahrenheit and their water was completely boiling they dropped an ice cube inside.

As soon as they drop the ice cube inside they took a picture of the beaker of water and thermomemter. This picture also becomes evidence.

This picture is evidence that shows whether or not the water stopped boiling or continued boiling when the ice cube was dropped inside. (the water stops boiling by the way)

Students also used the thermometer to record a temperature change when the ice cube was added.

Did the temperature decrease, increase, or stay the same? The temperature decreased and the water stopped boiling.

Evidence #1: Now, they had 2 pieces of evidence. They had a picture showing what happened to the boiling water then the ice cube was added to it.

Below are a few pictures that I took from CER’s that were completed in my class:

• 

• 

Evidence #2: The other piece of evidence I required was a data table. Student did the activity 3-4 trials and for each trial they had to record the boiling water temperature and the temperature after adding 1 ice cube.

Below is a typical examples of what some of my 8^th grade students submitted:

How To Write The Reasoning Section Of A CER

Alright, at this point we have made a Claim and have collected Evidence, their data table and pictures.

Reasoning: The reasoning section is where the connection between the Claim and Evidence is made.

In this section you should encourage (when possible) that students stick to scientific rules, laws, principles, or definitions.

What you don’t want students to do is again just reword their Evidence, we already know what their evidence is, it is in the evidence section of the CER. They need to describe how their evidence confirms their Claim as accurate or inaccurate.

 Let’s look at a poorly written reasoning section and a few well written ones.

Note: Keep in mind that the students did have some background knowledge of thermal energy and energy transfer from researching prior to doing this activity.

Also, this is when the student can acknowledge if their claim was accurate or not.

Well Written Reasoning: (I took these from actual student CER’s)

Sample 1: “Yes, my claim was accurate. When the ice cube was added to the boiling water, the high energy from the water transferred into the ice, as it was a lower temperature. I did 4 trials and in each trial the temperature of the boiling water went from 100 degrees to about 70 degrees. Once the ice cube melted and reached equilibrium with the boiling water, the water returned to a boiling state.”

Sample 2: “My claim was inaccurate. My data doesn’t support my claim because my claim said the water would keep boiling, but my data shows that the water stops boiling after putting the ice cube in. In all 3 trials the water temperature decreased from 212 degrees to about 175 degrees. The water stops boiling as soon as I put the ice cubes in, then starts to reboil after the ice cube is melted. The boiling water is higher energy than the ice cube, so when adding the ice cube into the boiling water, the high energy transfers from the boiling water to the ice cube. This makes the water stop boiling, because it is using its energy to transfer to the ice cube’s lower energy.

Poorly Written Reasoning: ( I took from actual student CER’s)

Notice that these Reasoning responses lack the scientific connection of thermal energy and/or energy transfer in these examples. Also, they do not reference their evidence/data in any way.

A good CER must cite specific evidence/data.

Sample 1: “My claim was not accurate is because when I put the ice cube in the hot boiling water, it started to cool off, after the ice melted in the boiling water, it stopped boiling.”

Sample 2: “ This happened because the water was so hot that the 1 ice cube was nothing to it and then after putting more it was making it stop since it was starting to become colder”

Sample 3: “The water boiled and when I put an ice cube in it stoped boiling for a minute. The water stopped boiling for a little bit because the ice is cold and the water reacts by not boiling but then it starts up again.

Again, look at how the well written reasoning make the connection to thermal energy and energy transfer correctly.

I can conclude that these students understood the energy transfer between the ice and the boiling water and how it impacted boiling.

Who Created The CER Framework?

The CER framework was founded by Katherine McNeil and Joseph Krajcik.

 If you want to find out everything there is to know about the CER framework then this book (Amazon link) that they co-wrote is the the one to buy.

Remember that a CER is simply a way to have your students investigate a claim of any kind and come up with data that is going to help them decide if they think the claim is accurate or inaccurate.