Unit Plan 15 (Grade 6 Science): Sediments, Fossils & Earth’s History

Focus: Use sediments, sedimentary rocks, and fossils as evidence to explain how past environments and geoscience processes are recorded in rock layers over different spatial and temporal scales.

Grade Level: 6

Subject Area: Science (Earth & Space Science — Earth’s Systems & History of Earth)

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

I. Introduction

In this unit, students learn to “read the rock record” to understand Earth’s history. They investigate how weathering and erosion create sediments, how deposition, burial, and cementation form sedimentary rocks, and how fossils and rock layers (strata) preserve clues about past environments (e.g., oceans, rivers, deserts). Students use models, diagrams, and rock/fossil examples to connect the rock cycle and surface processes to changes in Earth’s surface over long time scales, aligned with MS-ESS2-1 and MS-ESS2-2.

Essential Questions

• How do sediments and sedimentary rocks record information about past environments on Earth?
• In what ways do fossils help scientists reconstruct what living things and ecosystems were like long ago?
• How do geoscience processes like weathering, erosion, deposition, burial, and uplift change Earth’s surface at different spatial and temporal scales?
• How does the rock cycle connect processes happening at Earth’s surface and interior to the formation of new rocks and landforms?
• Why is it important to use evidence from rocks and fossils when constructing explanations of Earth’s past?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Describe how weathering and erosion create sediments, and how deposition, compaction, and cementation form sedimentary rocks as part of the rock cycle.
2. Identify and interpret basic sedimentary features (e.g., grain size, sorting, layering) to infer past environments (e.g., river, beach, deep ocean, desert).
3. Explain how fossils and their position in rock layers provide evidence for organisms, climate, and environmental conditions in the past.
4. Use models and diagrams to show how geoscience processes (weathering, erosion, deposition, burial, uplift) change Earth’s surface over short and long time scales and across different spatial scales (local to regional).
5. Construct an evidence-based explanation of how a sequence of rock layers and fossils records changes in an area’s environment and surface processes, aligned with MS-ESS2-1–2.

Standards Alignment — 6th Grade (NGSS-based custom)

• MS-ESS2-1 — Develop a model to describe the cycling of Earth’s materials and the flow of energy that drives this process (e.g., weathering, erosion, deposition, burial, melting, uplift, rock cycle).
  • In this unit: students model how sediments form from older rocks and are transformed into sedimentary rocks, linking surface processes (weathering/erosion) and internal processes (burial, uplift).
• MS-ESS2-2 — Construct an explanation based on evidence for how geoscience processes have changed Earth’s surface at different spatial and temporal scales.
  • In this unit: students explain how layered rocks, sediment deposits, and fossils record long-term changes in environments and landforms.

Success Criteria — Student Language

• I can describe how sediments form from older rocks and become sedimentary rocks in the rock cycle.
• I can use layering, grain size, and sediment type to make a reasonable claim about a past environment (like a river, beach, or ocean).
• I can explain how fossils in rock layers show what kinds of organisms lived in an area and what the environment was like.
• I can use models and diagrams to show how geoscience processes changed Earth’s surface over long periods of time and across different scales.
• I can write or present an explanation that uses evidence from sediments, rock layers, and fossils to tell a “story” about an area’s Earth history.