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Weathering Breaks Rocks

Grade 4 Earth Science — Shaping Earth’s Surface | Unit 1, Lesson 1 of 6

📚 Grade: 4th Grade⏱️ Duration: 45–60 minutes🔬 Subject: Earth Science — Shaping Earth’s Surface
🪨🌬️💧
Wind, water, ice, and roots can slowly break rock into smaller pieces.
📋 NGSS Standard:
4-ESS2-1 — Make observations and/or measurements to provide evidence of the effects of weathering or the rate of erosion by water, ice, wind, or vegetation. / 4-ESS2-2 — Analyze and interpret data from maps to describe patterns of Earth’s features.

🎯 Learning Objective

Students will explain how weathering changes rock at Earth’s surface and use evidence from simple observations to describe that change.

💡 The Big Idea

Weathering is the process of breaking rock into smaller pieces. It can happen slowly through water, ice, temperature changes, and living things.

🔬 The Science

Science Snapshot
rock in placeweathering actsrock breaks smallersediment becomes available
Weathering makes the loose material that later Earth processes can move.

What is happening?

Weathering breaks rock into smaller pieces without transporting those pieces away. It can happen through freezing and thawing, rubbing, root growth, chemical reactions, or repeated temperature changes.

Why it works that way

The important idea is that weathering changes the size or surface of the rock in place. Once the material is loosened, it is more likely to be moved later by erosion.

Look for this in the lesson

Students should pay attention to the evidence of rock change itself: cracks, roughness, crumbling, or sediment. Those observations are what support the explanation.

Ask while you read: Which observation is the clearest sign that weathering occurred before erosion?

📦 Materials

🏠 Household Items to Gather

📋 Printables

🧪 Investigation

Step 1 — Look closely at a rock sample (10 min)
Observe shape, texture, cracks, and edges. Record what you notice before anything changes.
Step 2 — Model rock breaking (10 min)
Gently break a cracker or dry bread piece and compare the larger and smaller pieces.
Step 3 — Connect the model to real weathering (10 min)
Discuss how roots, water, freezing, and heating can make cracks bigger over time.
Step 4 — Sort causes and effects (10 min)
Students match each weathering cause to the kind of rock change it can produce.
Step 5 — Write an evidence sentence (10 min)
Students explain one cause-and-effect example using words like because and so.

💬 Discussion Questions

How is weathering different from a rock just being moved?Weathering is about breaking or changing the rock first.
What evidence shows that a rock has weathered?Students may notice smaller pieces, cracks, rough edges, or crumbs.
How can water cause weathering?Water can enter cracks, freeze, or slowly wear minerals away.
Why does weathering matter for landforms?Weathering creates the smaller material that erosion can later move.

🚀 Extensions

Extension: Look for one example of weathering outside, such as cracked concrete, tree roots lifting a sidewalk, or rough worn stone.

👩‍🏫 Parent/Teacher Notes

Teaching move: Keep weathering and erosion separate in student language. Today is about the breaking and changing step.

Misconception to catch: Students often think weathering only happens in dramatic storms. Remind them that slow changes over long times also count.

Student Worksheet

Name: ________________________     Date: ________________________

Show how weathering changes a rock

Use drawings and evidence to show how a rock can break into smaller pieces over time.

CauseWhat could happen to the rock?What evidence would you look for?
Water in a crack
Plant roots growing
Heating and cooling

2️⃣ Draw before and after

3️⃣ Write a cause-and-effect sentence

🔑 PARENT ANSWER KEY — Detach before giving worksheet to students

Sample ideas

Water in cracks can make cracks wider. Roots can push rocks apart. Heating and cooling can weaken rock surfaces over time.

✅ What Success Looks Like