Knowledge points that must be memorized in the first book of science in grade four

Knowledge points that must be memorized in the first volume of science in grade four;

I. Weather and climate

Weather refers to the regional meteorological conditions in a short time, such as sunny, rainy, cold and hot. On the other hand, climate describes the long-term weather conditions in an area. Words commonly used to describe the weather are: sunny, cloudy, cloudy, rain, snow, fog and so on. Common weather phenomena are wind, rain, snow, thunder and lightning, etc., which are all formed by water vapor in the atmosphere.

The change of seasons is caused by the rotation of the earth, while the change of day and night is caused by the rotation of the earth. A thermometer is a tool for measuring temperature. Commonly used thermometers are centigrade thermometer and Fahrenheit thermometer.

Second, the growth and change of plants.

Plants need sunlight, water, air and nutrients for their growth. The growth process of plants includes seed germination, growth, flowering and fruiting. Plants have many ways to adapt to the environment. For example, cactus in the desert has thick stems and few leaves, which reduces water loss. Plant propagation methods include seed propagation and asexual propagation. The morphological characteristics of plants are closely related to the growth environment. For example, the needles of pine leaves can reduce the evaporation of water.

Third, the characteristics and habits of animals.

Animals can be divided into vertebrates and invertebrates according to their characteristics. Mammals have mammary glands, which can feed their young, such as humans, cats and dogs. The physical characteristics of birds include feathers, beaks and wings. They can fly. The physical characteristics of reptiles include scales, limbs and cold blood, such as snakes and lizards. Animal behavior habits include foraging, reproduction, defense and so on. For example, foxes have a cunning character and often steal food from other animals.

Fourth, the nature and change of matter.

Matter can be divided into solid, liquid and gas, and they can be transformed into each other. The properties of substances include color, smell, taste, hardness and so on. For example, metals have luster and ductility, which can be used to make various appliances. The solubility of a substance refers to its solubility in a solvent, and different substances have different solubility.

Changes in matter include physical changes and chemical changes. Physical change refers to the change of the state or shape of a substance, while chemical change refers to the change of the composition or properties of a substance. Some common chemical reactions, including combustion, fermentation and oxidation, are accompanied by energy conversion. For example, combustion requires the participation of oxygen and gives off light and heat.