CER Writing
Learn
Scientists do not just find answers - they also explain what they learned. CER helps you explain your discoveries like a real scientist!
What Is CER?
CER stands for three important parts:
- C = Claim - What you found out (your answer)
- E = Evidence - What you saw or measured (your data)
- R = Reasoning - Why the evidence supports your claim (your thinking)
The Claim
A claim is your answer to a question. It tells what you discovered. A good claim:
- Answers the question you were investigating
- Is one clear sentence
- Does NOT say "I think" - it says what IS true based on your investigation
The Evidence
Evidence is the proof from your investigation. It is what you saw, counted, or measured. Good evidence:
- Comes from your investigation (not from guessing)
- Uses numbers or specific details
- Is true and accurate
The Reasoning
Reasoning explains WHY your evidence proves your claim. It connects everything together. Good reasoning:
- Explains how the evidence supports the claim
- Uses words like "because," "so," or "this shows that"
- Makes sense to someone who reads it
Examples
Example 1: The Ice Cube Investigation
Question: Does ice melt faster in the sun or in the shade?
Claim: Ice melts faster in the sun than in the shade.
Evidence: The ice cube in the sun melted in 10 minutes. The ice cube in the shade took 25 minutes to melt.
Reasoning: The sun ice melted 15 minutes faster because the sun makes things warmer. Warmer things make ice melt faster. This shows that the sun speeds up melting.
Example 2: The Plant Water Investigation
Question: Do plants need water to grow?
Claim: Plants need water to grow.
Evidence: Plant A got water every day and grew 5 inches tall. Plant B got no water and only grew 1 inch, then turned brown.
Reasoning: Plant A grew much more than Plant B because it had water. Water helps plants stay healthy and grow. The plant without water stopped growing and turned brown, which shows it was not healthy.
Example 3: The Magnet Investigation
Question: Do magnets stick to all metals?
Claim: Magnets do not stick to all metals.
Evidence: I tested 5 metal objects. The magnet stuck to the paper clip, nail, and scissors. The magnet did NOT stick to the penny or the aluminum foil.
Reasoning: Only 3 out of 5 metal objects were magnetic. This shows that magnets only stick to some metals, not all of them. The penny and foil are made of different metals that magnets cannot pull.
Practice
Answer these questions about CER writing.
1. What does the "C" in CER stand for?
A) Cookie
B) Claim
C) Color
D) Count
2. What does the "E" in CER stand for?
A) Elephant
B) Eating
C) Evidence
D) Exit
3. What does the "R" in CER stand for?
A) Running
B) Reasoning
C) Reading
D) Red
4. Which part of CER answers the question?
A) Claim
B) Evidence
C) Reasoning
D) None of them
5. In the ice cube example, what was the evidence?
A) Ice is cold
B) The sun ice melted in 10 minutes, the shade ice in 25 minutes
C) Ice is made of water
D) The shade was dark
6. Which sentence is a CLAIM?
A) I think maybe plants like water
B) Plants need water to grow
C) Plant A got water every day
D) Because water helps plants
7. Where does evidence come from?
A) From guessing
B) From your investigation
C) From your dreams
D) From making things up
8. What does reasoning explain?
A) What you had for lunch
B) Why the evidence supports the claim
C) What color the sky is
D) How to ride a bike
9. Read this: "The magnet stuck to 3 out of 5 metal objects." Is this a claim, evidence, or reasoning?
A) Claim
B) Evidence
C) Reasoning
D) None of them
10. Read this: "This shows that magnets only stick to some metals." Is this a claim, evidence, or reasoning?
A) Claim
B) Evidence
C) Reasoning
D) None of them
11. Mia did an investigation about bouncing balls. Her claim is "The rubber ball bounces higher than the tennis ball." What should she write next?
A) Her favorite color
B) Her evidence (how high each ball bounced)
C) A story about a cat
D) What she ate for breakfast
12. Why do scientists use CER?
A) To make their writing longer
B) To explain their discoveries clearly
C) To confuse people
D) Because their teacher said so
Check Your Understanding
Think about these questions:
- Can you remember what C, E, and R stand for?
- What makes good evidence?
- Why is reasoning important?
- Can you write a simple CER about something you have investigated?
Next Steps
- Practice writing CER statements about investigations you do
- Remember: Claim answers the question, Evidence is your data, Reasoning explains why
- In the next lesson, you will take a Unit Checkpoint to show everything you have learned!