What Is Claim Evidence Reasoning?

“So… what do I write?” 

“I don’t know...I just made a lame guess.” 

That is a teaching nightmare — students who are completely lost despite your best attempts. Getting students to move beyond random guessing (or worse, complete silence) can feel like pulling teeth. Sometimes students are at a total loss, and despite all your lesson planning and Pinterest-boarding, maybe you are too. 

How can we help students engage meaningfully with science, think deeply about their experiments, and really get something out of a lesson, without just giving them the answers?

With the Claim-Evidence-Reasoning (CER) framework, something will change in students. Suddenly science class may be a little louder, but with structure, ideas, and collaboration. Students will actually know what to say instead of making “a lame guess.” 

The Claim Evidence Reasoning teaching model is a structured framework that pushes students to think more deeply about scientific instruction and experiments. CER will introduce students to not only thinking about what happened but why it happened, creating a deeper level of inquiry. While students are pushed to think more deeply, CER also provides a clear structure for students to use claims, give relevant evidence, and reason like a true scientist.

Through implementing CER, science education can be more than fun experiments; it can become an exercise in critical thinking skills. Students will learn to determine cause and effect, analyze critical data, and interpret results. All of these skills combined will lead to an opportunity for students to synthesize their findings and learn to employ argumentative reasoning in their work. Whether in the science classroom or not, these elements of CER writing will transfer into writing skills for any class or topic. 

Why Students Struggle With CER (and How Teachers Can Help)

The CER format is a powerful tool for building up critical thinkers, but that doesn’t mean it will come easily. There are a few common challenges students may face with CER lessons, such as: 

Being Vague
Sometimes, students struggle to create a research question or write a claim with depth. For example, a student may write, “Sunlight is good” rather than using evidence reasoning to  say, “Plants that were exposed to sunlight for an hour longer than other plants grew five extra inches in a week, showing that sunlight is critical for plant growth.” To overcome this, try providing some sentence starters to get students going. Providing a structured starting point can help students know where to begin with their questions or analysis of the scientific principles at play. 

Knowing Evidence from Reasoning
Sometimes students may confuse raw data (evidence) with the scientific explanation (reasoning). Maybe a student includes a graph as evidence but doesn’t explain how it supports the claim. To help students identify each component of the CER process, have them highlight each part in a different color, either from a sample paragraph or another student’s work. When they can identify the components in others’ writing, it will be easier to implement them in their own writing process. 

Saying “I don’t know.”
This can become the default when asked to make a claim or support their reasoning. Resorting to this answer may be due to uncertainty, fear of being wrong, or a lack of confidence. Help students build their confidence by providing low-stakes time to think. In pairs or small groups, encourage students to talk together before committing to their CER responses. Students should also understand that uncertainty is an important part of scientific thinking. They don’t have to be right about what exactly is going on, but they just need to think about what might be happening, and why it’s happening that way. 

At any stage of learning, whether middle school students doing their first chemistry experiment or high school students getting ready for an AP Biology test, support is necessary. Introduce CER and its value for the scientific method through modeling and practice. Students may feel a little shaky at first when writing explanations, but patience and support from a teacher are the perfect key to helping them feel more confident and able. 

Why Teachers Should Use the CER Framework

CER helps students make sense of data. It’s more than just reporting what happened. Instead of saying,  “The temperature got hotter,” students will ask themselves: By how much did the temperature rise? Why did that happen? What does this mean? This is where the magic happens because students aren’t just filling out worksheets or making graphs; they’re developing real analytical skills.

When students make the connection that evidence supports claims, they see that conclusions come from data, not only opinions. This will help them slow down and learn to analyze before jumping to conclusions, which is essential far beyond the science classroom. 

CER also aligns naturally with the Next Generation Science Standards, which prioritizes scientific practices like building explanations and creating arguments grounded in evidence. CER exposes students to these skills repeatedly in an intentional way. As an added bonus, these skills strengthen their writing skills as a whole, not just in science. CER helps students write clearly, think logically, and argue persuasively. The more they practice organizing their thoughts with CER, the more confident and capable they become

How Mission.io Makes CER More Engaging

I know what you’re all thinking here—CER seems great, but asking students to write explanations on a worksheet doesn’t always have students jumping for joy. But what if you could turn CER into a challenge, a mystery, or a mission?

That’s exactly what Mission.io does. Through Missions such as On The Edge of Tomorrow or The Abyss, writing with strong reasoning and evidence is built into stories and adventures where students can investigate real problems. They aren’t just writing to fill up a page, but they’re writing to solve a problem, rescue a town, or save a species. 

Missions have built-in group activities, interactive data, and prompts that make writing explanations feel natural and purposeful. Because the tasks are connected to a larger story, students are more invested in getting it right. 

Using CER to Support the Scientific Method

CER also complements the scientific method by incorporating the critical steps of inquiry: ask a question, collect evidence, and explain results. CER simply adds structure to student reflection and encourages them to think more deeply about the results and their analysis. 

Through CER, students move from observing to interpreting, a key switch that makes students true scientific thinkers. 

A strong reasoning statement is the glue that connects the claim and the evidence to real science. Here is the chance for students to apply class concepts, reference vocabulary, and tie it all back to scientific laws and theories. Deeper exploration pushes students to synthesize, not just repeat back to you the latest scientific rule they learned. When students can see these laws at play and start making connections on their own, you know they are truly learning. 

Building Better Thinkers With CER Lessons

Students who engage with CER regularly become more independent and thoughtful learners. Instead of waiting for the right answer or for someone else to tell them, they begin building their own conclusions through logic and data.

And let me tell you, that mindshift is huge! Over time, it builds not just better writers, but better scientists, thinkers, and citizens. 

Better yet, don’t just limit CER to lab reports. It works like a charm in project-based learning, where students can explore a real-world problem, gather information, and propose solutions. Incorporate CER into STEM challenges, environmental investigations, or even design tasks. Focus on students presenting their findings with claims, textual evidence, and reasoning that explains the science behind their conclusions. 

Cross-Curricular Connections With CER

I’ve been saying it all along but I’ll say it again: CER doesn’t just benefit science! It can belong in every subject and grade. In ELA, students already learn to support claims with textual evidence. During social studies, they analyze sources (evidence) and write arguments. The structure of CER mirrors and strengthens what they do in other subjects, just with different content.

By collaborating with other subjects, you can help students internalize CER into their everyday thinking process. They can see it’s a universal academic tool and not just a science writing trick. 

One of the best aspects of CER is that it teaches students to organize and articulate complex ideas. Over time, this improves more than just their writing. It improves their speaking, presenting, and . Whether answering a constructed response or explaining their thinking in a discussion, students who’ve practiced CER will feel more prepared and confident.

Tips to Improve CER Writing Over Time

Your students won’t be CER experts after one experiment. Start small. Break it into pieces. Model each step and provide them with sentence starters and examples. Give them time to think out loud or discuss with a partner.

Also consider the power of color-coding, anchor charts, and sample paragraphs. Let students practice giving and receiving feedback. Each time, they’ll get better and quicker.

But most importantly? Make CER routine. If students know that their CER explanations will be written at the end of a lesson, they’ll be looking out for the claims, evidence, and reasoning they can write about during the entire lesson. The more they engage with it, the more natural it will become. 

It doesn’t have to be a full essay or research report every time. CER can be short and focused. Practice it as an exit ticket or a reflection task to keep it simple and low-pressure. If students can do it in the low-stakes situations, they will feel more prepared to take on the bigger tasks. 

Turn CER Into a Launchpad for Scientific Thinking

CER is more than writing better paragraphs. It’s about building a better mindset. Asking questions, gathering data, and explaining thinking are essential elements to critical thinking and life-long learning. Whether you’re using Mission.io, designing your own lesson, or doing age-old classic experiments, embedding CER daily into class transforms lessons from passive to powerful.

With time and practice, students won’t just survive in science class — they’ll thrive in it.