How to write an argument using Claim, Evidence, Reasoning (CER)
Claim: A statement or conclusion that answers the original question or problem.
Evidence: Scientific data that supports the claim. The data need to be appropriate, sufficient, and free of inference to support the claim. Evidence does not include generalizations and beliefs about the data.
Reasoning: A justification that connects the evidence to the claim. It shows why the data count as evidence by using appropriate and sufficient scientific principles.
*Rebuttal: A description of alternate explanations which provides counter evidence and reasoning why the alternate explanation is not the most appropriate explanation for the question or problem.
After completing the laboratory investigation and analyzing the data, answer the question or problem posed at the beginning of the investigation (claim). Determine what data from the experiment support the claim. Do not simply state the data support the claim but write several sentences with specific, appropriate and sufficient data – the actual numbers or observations from the experiment. Then, using appropriate and sufficient scientific principles, explain why the evidence supports the claim.
If you have more than one question to answer (and thus claim to make), be sure to include evidence and reasoning for each claim.
* A rebuttal is another valuable component to an argument, but will not be required in lab reports.