Unit Plan 24 (Grade 2 Science): Slow vs. Rapid Changes Review

Focus: Compare slow Earth changes (layering, weathering, erosion) with rapid events (landslides, floods) using models, pictures, and simple texts, and revisit solutions that help slow or prevent erosion.

Grade Level: 2

Subject Area: Science (Earth Science • Earth’s Surface Processes)

Total Unit Duration: 5 sessions (one week), 30–45 minutes per session

I. Introduction

In this review unit, students pull together what they have learned about Earth’s changing surface. They explore slow changes like rock layering, weathering, and erosion, and compare them with rapid changes such as landslides and floods. Using picture cards, short texts, and simple sand/soil models, they decide whether changes happen slowly over many years or quickly in minutes or days.

Students also revisit simple erosion solutions (rocks, walls, plants, barriers) and explain how these can slow or prevent wind and water from changing the land. By the end of the unit, they can use evidence from observations and sources to tell the difference between slow vs. rapid changes and describe ways people can protect the land.

Essential Questions

• How can Earth’s surface change slowly over time, and how can it change quickly during events like landslides or floods?
• What is the difference between weathering, erosion, and layering, and why are these considered slow changes?
• How do landslides and floods change the land rapidly, and what problems can they cause for people and places?
• What are some solutions that help slow or prevent wind and water from changing the shape of the land, and how can we compare which ones work better?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Use information from pictures, readings, and videos to tell whether an Earth event is a slow change (layering, weathering, erosion) or a rapid change (landslide, flood).
2. Describe layering as rocks or sediments building up over time, and weathering/erosion as processes that break down and move rock or soil.
3. Model at least one slow change (e.g., building layers of sand/soil) and one rapid change (e.g., a small “landslide” or “flood” in a tray).
4. Identify and explain at least two solutions designed to slow or prevent wind or water erosion (e.g., rocks, walls, plants, fences).
5. Use observations and simple notes to compare solutions, stating which one worked better at protecting the land and why.

Standards Alignment — 2nd Grade (NGSS-Aligned)

• 2-ESS1-1 — Use information from several sources to provide evidence that Earth events can occur quickly or slowly.
  • Example: Sort and explain slow changes (layering, weathering, erosion) vs. rapid changes (landslide, flood) using pictures, models, and short texts.
• 2-ESS2-1 — Compare multiple solutions designed to slow or prevent wind or water from changing the shape of the land.
  • Example: Test and compare a bare sand hill vs. a hill with rocks, walls, or “plants” to see which one erodes less.

Success Criteria — Student Language

• I can tell whether an Earth change is slow (like weathering, erosion, layering) or rapid (like a landslide or flood).
• I can describe or model how Earth’s surface changes slowly over time and quickly during big events.
• I can name and draw at least two erosion solutions, such as rocks, walls, or plants, and tell what they are trying to do.
• I can compare my solutions and say which one slowed erosion more, using my observations or simple notes.
• I can explain my ideas with pictures, labels, and words so someone else can understand.