Unit Plan 29 (Grade 7 Science): Comparative Anatomy
Compare modern and fossil structures to reveal similarities, differences, common ancestry, and adaptations—evidence for evolutionary relationships over time.
Focus: Apply scientific ideas about structures and functions to construct explanations for similarities and differences among modern organisms and fossil organisms as evidence for patterns of relatedness and adaptation.
Grade Level: 7
Subject Area: Science (Life Science — Biological Evolution & Evidence)
Total Unit Duration: 5 sessions (one week), 50–60 minutes per session
I. Introduction
In this unit, students explore comparative anatomy—the study of body structures—to understand how organisms can be similar yet also different. Using diagrams, bone models, and fossil images, they compare structures such as limbs, skulls, and fins across a range of vertebrates (and some invertebrates) to see patterns in how structures are arranged and used. Students then use these patterns to construct explanations about possible common ancestry, adaptation, or different evolutionary paths. The unit culminates in a Comparative Anatomy Evidence Explanation aligned with MS-LS4-2.
Essential Questions
- How can similar structures (like forelimbs) in different organisms provide evidence that they might share a common ancestor?
- Why do some organisms have similar structures but different functions, while others have different structures but similar functions?
- How can comparisons between modern organisms and fossil organisms help us explain change over time?
- What is the difference between homologous and analogous structures, and how do these patterns support different scientific explanations?
II. Objectives and Standards
Learning Objectives — Students will be able to:
- Identify and label major anatomical structures (e.g., forelimb bones, skull features, fins, wings) in diagrams of modern and fossil organisms.
- Use comparative anatomy charts to describe similarities and differences in structure among multiple organisms.
- Distinguish between homologous structures (similar structure, possibly different function) and analogous structures (different structure, similar function) and identify examples in data sets.
- Construct written or oral explanations that use structural similarities and differences to support ideas about common ancestry, adaptation, or distinct evolutionary histories.
- Develop a Comparative Anatomy Evidence Explanation (poster, one-pager, or slide) that integrates structural comparisons between modern and fossil organisms, aligned with MS-LS4-2.
Standards Alignment — 7th Grade (NGSS-based custom)
- MS-LS4-2 — Apply scientific ideas to construct explanations for similarities and differences in modern organisms and fossil organisms to infer evolutionary relationships and patterns of change.
- Example: Compare limb structures of modern mammals and fossil reptiles to explain possible common ancestry.
Success Criteria — Student Language
- I can label and describe major body structures in diagrams of modern and fossil organisms.
- I can use charts or tables to compare structures and clearly state how they are similar and how they are different.
- I can tell whether a pair of structures is more likely homologous or analogous, and explain why.
- I can write or present an explanation that uses comparative anatomy evidence to support ideas about relatedness or adaptation.
- I can clearly connect modern and fossil examples to show how structures have changed or persisted over time.