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Science - 4th Grade
Standard 3 Objective 2
These classroom activities will help students understand 4 types of weather processes: wind, running water, plant growth, and freezing water.
Worksheets for each studentActivity 1 Materials
Soils form over millions of years from parent material that is broken down by weathering from wind, water, temperature, chemical changes, and living organisms. Over time, glaciers move over the land and grind rocks together, rubbing off particles of all sizes. By day, rocks are warmed by the sun and expand, while at night the rocks cool and contract.
Over time, enough expansion and contraction cause rock particles to chip off. In cold temperatures water in the cracks of rocks freezes and expands, causing the rocks to break into smaller pieces. Plant roots will grow into "soft" rock and cause them to break. Water and wind wear away at rocks carrying tiny bits of rock along until they get trapped by soil.
Many rocks are broken apart by lichens. Lichens are tiny crusty, coral-like plants (green, orange, gray, etc.) that live on rocks. These tiny plants secrete an acid that dissolves some minerals and breaks down the rock. Decaying plants and animals are organic matter. Organic matter is also acidic. When water and organic matter mix, they form a slightly acidic solution that breaks down rocks in soil That is why soils in the eastern United States are more acidic than the soils in the West. They contain more organic matter.
Organic matter is good for plants. It keeps topsoil in its place, keeps soil particles together, retains soil moisture, and speeds up soil formation. It takes between 100 and 500 years for just one inch of topsoil to form, depending on the type of rocks and climate.
1. Use a Science Process and Thinking Skills
Pre-Assessment/Invitation to Learn
Ask the students to consider thee questions: Which is stronger, a plant or rock? Is water stronger than a rock? Would you expect water to damage or break apart large rocks?
Students should draw diagrams illustrating each of the following types of weathering processes. Some of these will occur over a period of days and weeks. They should draw and label a series of diagrams to show the progression of weathering.
Activity 1 - Wind as an agent of weathering
Activity 2 - Running water as an agent of weathering
Activity 3 - Plant growth as an agent of weathering
Activity 4 - Freezing water as an agent of weathering
Homework & Family Connections
Find examples of weathering around the home and on trips. Make a photo album showing examples of all types of weathering.
Take a tour around the school grounds to look for evidence of weathering.
Show pictures and categorize types of weathering illustrated.