You probably don't think about soil often, but the following report may help you learn about science of soil.

What is soil made of?

Soil is made of sediments (沉积物) and humus(腐殖质). Sediment is small pieces of rock broken down over time by rain, ice, and wind. Sediment is often found in water. Humus comes from decayed(腐烂的) plants and animals. It helps give plants a lot of the food they need to grow.

How does soil form?

Over centuries, rock breaks down into very small pieces.

The rock pieces mix with humus.

The humus gets thicker and thicker over time. Soil is formed(形成)l

How are soils different?

Soils can be different colors and have different textures(质感). Texture is how the surface of an object feels. Color and texture are two features(特征) of soil.

Plants and soil

Plants do not grow well in some soils. Sandy soi1 is too dry. It does not hold water. Soil with too much clay is too thick. Most plants grow well in dark, rich garden soil that has different sediments and a lot of humus in it.

In most parts of the world, many students help their schools make less pollution. They join "environment clubs". In an environment club, people work together to make our environment clear.
Here are some things students often do.
No-garbage lunches. How much do you throw away after lunch? Environment clubs ask students to bring their lunches in bags that can be used again. Every week they will choose the classes that make the least garbage and report them to the whole school!
No-car day. On a no-car day, nobody comes to school in a car--- not the students and not the teachers! Cars give pollution to our air, so remember: Walk, jog, bike or run. Use your legs! It's lots of fun!
Turn off the water! Do you know that some toilets can waste twenty to forty m³  of water an hour! In a year, that would fill a small river! In environment clubs, students mend those broken toilets. We love our environment. Let's work together to make it clean.