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Science - 4th Grade
Standard 3 Objective 3
This activity will help students understand the basic components of soil and relate the components to plant growth.
Soil is made up of particles of rocks and minerals, dead plant and animal matter, tiny living organisms, gases (air), and water. The particles of rocks and minerals found in soil have broken away from larger pieces of rocks and minerals. Some particles are large chunks of rock and others are tiny mineral particles, which get dissolved by water in the soil.
Soil contains space filled with water and gases (air). Water soaks in the ground from rain (and other forms of precipitation). Gases come from the air, plants, and animals. Water in the soil makes minerals available for plants to use.
Soil also contains organisms. Living organisms (such as bacteria, fungi, insects, etc.) are an important part of soil. Living organisms break down nonliving organic plants and animals in the soil, which makes soil rich and healthy for plants to grow in.
Every soil consists of minerals, organic matter, water, and air. The proportions may vary but the following list is the average composition of the major soil ingredients: 45 percent minerals, 25 percent water, 25 percent air, 5 percent organic matter (both living and dead).
Soil is important to plants. Soil holds plants in place and holds the water that plants need. Soil contains mineral nutrients that plants need in trace amounts to grow.
Soil is a critical resource. Most of our food crops are grown on soils that have taken millions of years to form. Food can be grown without soil, but we do not have enough hydroponic technology available to feed the world. It is important to prevent soil erosion to protect valuable soils.
2. Manifest Science Interests and Attitudes
4. Communicate Effectively Using Science Language and Reasoning
Pre-Assessment/Invitation to Learn
Ask students what they think soil is composed of. Generate a list containing mineral or rock particles, air, water, living and dead organisms. Ask students to make a pie chart showing how much of each they think soil contains. Ask them to save it and compare their answers at the end of the activity.
Activity 1 - Looking for Organic and Inorganic Material
Activity 2 - Water in the soil
Activity 3 - Air in the soil