What is Claim, Evidence, Reasoning (CER)?

Are you struggling to write clear and convincing answers in science class? You’re not alone. One of the most effective strategies used by top students to structure their responses is called Claim, Evidence, Reasoning (CER). This simple yet powerful writing framework is especially popular in science education, but it can also be used across subjects like English, History, and Social Studies. In this blog post, we’ll explain what CER is, why it’s important, and how you can master it to improve your writing skills and critical thinking. Whether you’re a Primary school student, a Secondary school student preparing for O-Levels, or a parent looking to support your child’s learning, this guide is for you!

What is CER (Claim, Evidence, Reasoning)?

CER stands for Claim, Evidence, and Reasoning. It is a writing strategy used to help students explain their answers clearly and logically.

Claim – This is your answer to the question or your main point.
Evidence – This includes the data, facts, or observations that support your claim.

Reasoning – This explains why your evidence supports your claim. It often includes scientific principles, logic, or theories.

Why is CER Important in Science and Beyond?

Using the CER framework trains students to:

Think critically
Use data and observations effectively
Structure answers logically
Write better science lab reports and comprehension answers
Prepare for exams like PSLE and O-Level Science

In Singapore’s MOE syllabus, students are often expected to justify their answers with scientific reasoning. That’s why mastering CER can make a real difference in scoring well.

How to Write a Strong CER Response (with Example)

Here’s a step-by-step breakdown of how to use CER to answer a question:

Question: Why does a cold can of soda become wet on the outside after being taken out of the fridge?

✅ Claim:

The water on the outside of the soda can is caused by condensation.

🔎 Evidence:

When the cold can is placed in the open air, water droplets form on the outside of the can.

💡 Reasoning:

The air around the can contains water vapor. When warm, moist air touches the cold surface of the can, the water vapor cools down and condenses into liquid water. This is a process called condensation.

👉 Pro Tip: Always connect your evidence to your reasoning. Don’t just describe what happened—explain why it happened using scientific concepts.

CER in Exam Questions and Lab Reports

Whether you’re writing a response to a science experiment, an open-ended question, or a data-based analysis, using the CER format helps structure your thoughts. Here are some places where CER writing is commonly used:

Science lab reports
Comprehension questions in Chemistry, Physics, Biology
Data-based questions in Geography or Social Studies
Argumentative essays (modified CER)

Tips to Master the CER Strategy

Underline the question keywords – Know what you’re being asked.
Start with a direct claim – No need to repeat the question.
Use specific and relevant evidence – Avoid vague statements.
Include scientific vocabulary – Use key terms from the syllabus.

Practice with different subjects – Try CER in English, Math, and Humanities too!

Final Thoughts: Why CER is a Must-Know for All Students

Learning to write using the Claim Evidence Reasoning format gives students a solid foundation in structured thinking. Whether you’re preparing for school exams, national assessments, or even real-life problem solving, CER helps students become more confident and logical thinkers.

At EduFirst Learning Centre, we regularly teach students how to apply CER in science and other subjects. With guided practice and the right strategies, anyone can master this writing technique.

What is Claim, Evidence, Reasoning (CER)?: A Student’s Guide to Writing Better Science Answers

What is CER (Claim, Evidence, Reasoning)?

Why is CER Important in Science and Beyond?