Unit Plan 28 (Grade 7 Science): Fossils & Earth’s Past

Focus: Analyze and interpret fossil data to document the existence, diversity, extinction, and change of organisms over deep time.

Grade Level: 7

Subject Area: Science (Life Science — Biological Evolution & Earth History)

Total Unit Duration: 5 sessions (one week), 50–60 minutes per session

I. Introduction

In this unit, students use fossils and rock layer data to reconstruct parts of Earth’s past. They work with diagrams, fossil cards, data tables, and timelines to document which organisms existed in different geologic layers, how diverse those communities were, and when major extinctions occurred. Students then look for patterns of change across time—such as the appearance, disappearance, or transformation of certain groups—and practice explaining what fossil evidence can and cannot show. The unit culminates in an evidence-based product aligned to MS-LS4-1.

Essential Questions

• How do fossils and rock layers provide evidence that different organisms existed at different times in Earth’s history?
• In what ways can fossil data help us describe diversity, extinction events, and changes in groups of organisms over time?
• What patterns do we see when we analyze fossil evidence from multiple layers or sites, and how do those patterns support ideas about Earth’s past?
• What are the strengths and limits of using fossil data to reconstruct the story of life on Earth?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Use fossil diagrams and rock layer cross-sections to identify which organisms existed in specific layers and time periods.
2. Analyze fossil data tables (counts, presence/absence) to describe changes in diversity and extinction across layers or time intervals.
3. Interpret graphs or timelines built from fossil data to identify patterns of change in at least one group of organisms (e.g., rise, peak, decline, extinction).
4. Explain how fossil evidence supports the claim that types of organisms have changed over time, including both extinction and the appearance of new groups.
5. Create a “Fossils & Earth’s Past” Evidence Poster or Brief that clearly uses fossil data to document existence, diversity, extinction, and change, aligned with MS-LS4-1.

Standards Alignment — 7th Grade (NGSS-based custom)

• MS-LS4-1 — Analyze and interpret data from fossils to document the existence, diversity, extinction, and change of life forms throughout Earth’s history.
  • Example: Use a fossil record from multiple layers to show when certain groups appeared, flourished, and disappeared.

Success Criteria — Student Language

• I can read a rock layer diagram or fossil chart and tell which organisms existed in each layer.
• I can use fossil data tables or graphs to describe how diversity changed and when extinctions occurred.
• I can identify at least one pattern of change (e.g., appearance, increase, decrease, disappearance) in a group of organisms across time.
• I can explain how fossil evidence supports the idea that life on Earth has changed over long periods.
• I can create a product that clearly uses fossil evidence (not just opinion) to tell part of Earth’s story.