Sample CER (Claim, Evidence, Reasoning) Based on NGSS Life Science Biology Standards

Claim, Evidence, and Reasoning are the three subsets that make up a CER graphic organizer. Each subgroup has a comprehensive breakdown of what that subset entails. So, with a simplistic, broad, complete subset, it is essential to understand the inner workings of each section. Below is a breakdown of each subgroup:

Claim: This is a statement you believe to be accurate based on the question. This statement is meant to solve the question or problem. This is also when the you must ensure that the claim answers the question. It is also time to ensure that your claim is a complete sentence and gives a proper rationale or explanation.

Evidence: This is where you enter all your data and findings. Evidence is the area for research, investigations, numbers, collections, videos, and anything else that has been gathered to either support or deny the given claim. While this area is being investigated, you must ensure that the evidence is relative to the claim.

Reasoning: Does the data support the claim? The reasoning is different from where the data is stated. Correlations are made about whether the claim is right or wrong. Have you started your evidence to support the claim? Did you record your findings in complete sentences?

Data Set:

  • Observation 1: A population of finches on an isolated island has shown a significant increase in beak size over the past 50 years, particularly during periods of drought.
  • Observation 2: During drought years, the availability of small seeds decreased, while the abundance of larger, harder seeds increased.
  • Observation 3: Genetic analysis of the finch population reveals that individuals with larger beaks had higher survival and reproduction rates during drought periods.
  • Observation 4: Fossil records and historical data indicate that beak size in this finch population has fluctuated in response to changes in food availability over the past millennia.

Example CER:

Claim: The increase in beak size among finches on the island is a result of natural selection driven by changes in food availability.

Evidence:

  • Data shows that during drought periods, small seeds become scarce while larger, harder seeds become more common.
  • Finches with larger beaks, which are better suited for cracking open large seeds, have higher survival and reproduction rates during these droughts.
  • Genetic analysis supports that larger beak size is heritable, and these traits are passed on to subsequent generations at a higher rate.

Reasoning: The principles of natural selection explain that in an environment where food sources change, traits that improve survival and reproduction become more common in the population. In this case, larger beaks are advantageous during droughts when only large seeds are available. Over time, the finch population evolves to have larger beaks as these individuals are more likely to survive and reproduce. This adaptation is a direct response to environmental pressures, demonstrating the process of evolution by natural selection.