三年级科学(下册各课知识点0)(国外英文资料).docVIP

三年级科学(下册各课知识点0)(国外英文资料) The third grade science (2 each course knowledge point 0) Unit 1 Soil and life The teaching content of soil and the life is one of the material specific content standards according to the primary school science curriculum standards in the content of the standard, the earth and the universe, the earths rocks, sand and soil to the organization, the purpose is to put the soil as a soil for the topic, an understanding of the material, using a variety of methods and a variety of senses to recognize an object, cultivate students observation ability. 1, the soil around us Let students observe that there are sand, stones, litter, insects, earthworms and so on in the soil. The soil is closely related to life. 2. Understanding the soil Know the soil is a mixture of rock particles, air, water and soil humus; that is divided into three categories: the sediment content in particular, sandy soil, clay content in the clay, and sand, silt and clay loam is almost the proportion of three. It can be proved by experiment that different kinds of soil have different water permeability and water content. 3, fertile soil The nutrients in the topsoil come from the remains of decaying plants and animals, which are called humus. The more humus, the more fertile the soil. Earthworms can not only loosen soil, but also make fertilizer in the soil, making their living environment more fertile and conducive to the growth of plants. Earthworms are beneficial insects, we should protect the earthworm. Earthworms are natural ploughs and experts in improving soil.. 4. Soil protection Soil is a layer of loose material that covers the earths surface. It provides food and water for plants. The soil also provides a habitat for animals. She is our common home for human beings and animals and plants. It is because of the soil that the beautiful and lovely world is here. Make the students know many human behavior is the destruction of the soil, such as deforestation, throw waste batte