CER all starts with a question asked by the teacher. This question is based on a phenomena or lab experience. The student's explanation or answer, as you may have guessed, will consist of three parts: a claim, the evidence, and the student's reasoning. A claim is a statement that answers the question. Start with a hook or attention getting sentence. Briefly summarize the texts • State your claim. Make sure you are restating the prompt. Include a topic sentence that restates your claim and your reason.