CERR Model for Science Writing C The claim is a testable statement or conclusion that answers the original question. E The evidence is the scientific evidence that supports the claim. Evidence must be both appropriate and sufficient to support the claim. (Does the evidence – the data—you present support the claim you are making?) R Reasoning is a justification that shows why the data counts as evidence to support the claim and includes appropriate scientific principles. R When explaining phenomena, there can be more than one possible claim or explanation. Often the same data can be used to support an alternate claim. You should learn to recognize alternative explanations. A good answer takes an alternate explanation into consideration and offers a rebuttal to why an alternative explanation is not appropriate. In other words, the rebuttal articulates why an alternative claim is not appropriate. It also gives you another chance to articulate your reasoning and lets the reader know you know what you’re talking about! As you develop as a scientist, your ability to make claims, cite evidence, use reasoning and offer rebuttals will become more sophisticated. I think this is a very useful tool for science writing.