Ancient Ancestry Assessment (Version 1)

13.B Construct a scientific explanation proposing relationships between all modern penguins and ancient penguins using the similarities and differences in accumulated body structure changes over time to estimate how relatively long ago they shared a recent ancestor.

13.B Construct a scientific explanation proposing relationships between all modern penguins and ancient penguins using the similarities and differences in accumulated body structure changes over time to estimate how relatively long ago they shared a recent ancestor.

Students’ written responses include explanations that use

natural selection in differing environments as well as the accumulation of mutations to explain the differences in body structures they observe,

the relationship between differences in body structure and lengths of time to justify which penguin species share recent ancestors, and

the relationship between differences in body structure and lengths of time to claim a species of penguin was either a direct ancestor of a certain modern penguin or group of penguins or that a species of ancient penguin went extinct.

If students are struggling to begin, encourage them to focus on how just two species of penguins are connected by a common ancestor, and then they may branch out from there. Make sure students are consulting their Penguin Ancestry Model as well as the General Model for Natural Selection the class developed previously. If you have given students Version 1: Ancient and Modern Penguin Explanation and you notice they are not supporting their claims with evidence and reasoning, you may choose to provide them a copy of Version 2: Ancient and Modern Penguin Explanation for additional scaffolding. If students are struggling to put their ideas in words, encourage them to include a drawing or model as part of their response to help clarify their writing.