Grade 3 (age 8-9)

Soil Observation

Soil forms over a very long time as rocks break into tiny pieces and dead plants and creatures rot and mix in. Rub it between your fingers and the grains differ: coarse sandy soil drains fast, while fine clay holds water a long time. Since each soil differs in grains and drainage, different plants grow well in each. On this page you can look at different soils and see how their grain size and drainage differ.

What does soil look like?

🔬 Look at soil closely

①Soil is rocks broken into tiny pieces

②Rock grains + decomposed life = soil

③Color, particle size, and feel differ by place

④Tiny creatures live inside soil

Layers of Soil

🏔️ Soil Layers

①Top: leaves and grass pile up

②Topsoil (humus): rich nutrients, plants grow well

③Subsoil: clay and minerals

④Gravel layer: rocks and gravel mixed

⑤Bottom: solid bedrock

Playground vs. Garden Soil

🌿 Two Soils Compared

①Playground soil: coarse, light, drains fast

②Garden soil: fine, dark, holds water

③Garden soil has lots of humus (dead matter), so it's dark

④Plants grow better in garden soil

Summary

How Soil is Made

Rock → Stone → Sand → Soil

Wind, rain, temperature change, and plant roots break rocks

Conditions of Good Soil

Fine grains + humus + right moisture

Soil like garden soil that holds nutrients and water

Role of Soil

Supports plant roots + supplies nutrients & water

Without soil, plants cannot grow

🎯 Key Points

①Soil is made when rocks break down

②Color, grain, and feel differ by place

③Garden soil is better for plants than playground soil

④Soil contains nutrients and tiny creatures

⑤Soil is essential for plants

Examples and Unit Test

Example 1

How does a hard rock become small bits of soil?

A rock slowly breaks apart from wind and rain, temperature changes, plant roots, and more.

As the rock breaks into stones and sand and becomes even smaller, it turns into soil.

▸ A rock breaks apart over a long time (rock → stones → sand → soil)

Soil is made when rock breaks into tiny bits.

Example 2

Between playground soil and garden soil, which grows plants better, and why?

Garden soil has fine grains, holds water well, and is rich in humus from decomposed organisms.

Playground soil has coarse grains, drains water fast, and has few nutrients, so plants grow better in garden soil.

▸ Garden soil (rich in nutrients and holds water well)

Garden soil, rich in humus and holding water, is better for plants.

Unit-test style

Which statement about soil is correct?

①Soil was made as soil from the very beginning

②Soil is made when rock breaks apart

③Playground soil has more nutrients than garden soil

④Garden soil drains fast, so plants grow poorly

⑤The color and grain of soil are the same everywhere

▸ ② Soil is made when rock breaks apart

Soil forms when rock breaks into tiny bits over a long time from wind, rain, and more.

Soil comes from rock (①), garden soil has more nutrients (③), garden soil holds water so plants grow well (④), and soil differs in color and grain by place (⑤).

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