Knowledge points of science encyclopedia in the first volume of the fourth grade of the Catalogue
Fourth grade scientific knowledge points
The first volume of the fourth grade scientific knowledge points
The sound of knowledge points in the first volume of science in grade four
1- 1 sounds are divided into high, low, strong and weak.
1- 1 Some sounds are pleasant and some are harsh.
1-2 An object moves back and forth repeatedly under the action of force, which is called vibration.
1-2 sound is produced by object vibration. When an object is acted by an external force, it does not necessarily make a sound, but only makes it vibrate. If you stop vibrating, the sound will stop immediately. )
1-2 Playing with a steel ruler, playing drums, striking sounds and meanings, and playing clarinet all make objects vibrate and make sounds.
1-2 There is an organ in our throat that can emit and control sounds-vocal cords. (P5)
When 1-2 sounds, the vocal cords become tight and vibrate rapidly. The tighter the vocal cords, the higher the sound.
1-3 sound can spread in all directions.
1-3 lightly touches the water surface with the struck sound and meaning, and the water surface will produce ripples, indicating that the tuning fork is vibrating.
1-3 Sound travels in the form of waves. When the sound wave meets an object, it will give an alarm to the object. This is how the sound passes through various substances. Spread from one place to another.
1-3 when an object vibrates, it will also cause the vibration of the surrounding substances, and the sound will be transmitted from one place to another through these substances.
1-3 Sound travels differently in different objects. Breeding speed: aluminum foil ruler > wooden ruler > nylon thread cotton thread
1-3 air is an important substance for transmitting sound, and it cannot transmit sound in a vacuum environment.
1-3 on the moon, because there is no air, that is, there is no substance that can transmit vibration, so even if two people are not far apart, they can't hear each other and must use radio equipment.
1-3 sound propagation speed in solid, liquid and gas.
1-3 The propagation speed of sound in the air is 340 m/s.
Our ears can be divided into outer ear, middle ear and inner ear. How do we hear sound: external sound > auricle > tympanic membrane of external auditory canal >; Auditory ossicles > cochlea > auditory nerve brain
1-4 The human external ear is like a tunnel, through which sound reaches the eardrum of Xiaoqizhen Zhong. The eardrum is very thin and elastic, and even a light sound really vibrates.
14 The external ear is composed of auricle and external auditory canal, the middle ear is composed of tympanic membrane and ossicles, and the inner ear is composed of cochlea, which is connected with auditory nerve.
1-4 function of auricle: collecting sound waves; Tympanic membrane: converts sound waves into vibration; Cochlea: Convert vibration into signal.
1-4 the vibration of the object drives the vibration of the surrounding air, which in turn causes the vibration of the eardrum. The ossicles transmit vibration to the inner ear and stimulate the auditory nerve to generate signals. When the brain receives the signal from the auditory nerve, we feel the sound.
1-5 Beat the sound and meaning with different dynamics, with a strong sound when tapped, and a weak sound when tapped.
The sound intensity of 1-5 can be described by volume. The volume is determined by the amplitude of the vibration of the object. The greater the vibration amplitude, the stronger the sound; The smaller the amplitude, the weaker the sound.
The sound level of 1-6 can be described by pitch. Pitch is determined by the speed at which the object vibrates. The faster the vibration, the higher the sound; The slower the vibration, the lower the sound.
1-6 The shorter, smaller, less and thinner objects vibrate faster and make higher sounds. The longer, bigger, more and thicker objects vibrate more slowly, and the lower the sound they make.
1-6 hits two tones of different sizes, with a small tuning fork emitting a high note and a large tuning fork emitting a low note.
1-6 When hitting nails with different lengths, the shorter the nail, the higher the sound.
1-6 When poking a steel ruler, changing the length of the ruler sticking out of the desktop will also change the pitch of the ruler when reporting the movement, because the speed at which the ruler reports the movement is changing.
Yes
1-6 The shorter the ruler sticks out of the desktop, the higher the sound it makes; The longer the ruler sticks out of the desktop, the lower the sound it makes.
1-7 when plucking the strings, the thinner the strings, the higher the sound; The thicker the string, the lower the sound.
1-8 Knock on glasses with different amounts of water. The less water, the higher the sound, and the more water, the lower the sound.
1-8 When pulling the rubber band, the tighter the rubber band, the higher the sound; The looser the rubber band, the lower the sound.
Breathing and Digestion of Scientific Knowledge Points in Grade Four
2- 1 Human respiratory organs are: nasal cavity, trachea, trachea, lung, diaphragm, etc.
2- 1 People's breathing is actually a kind of gas exchange, which makes oxygen enter the blood and expel carbon dioxide at the same time.
2- 1 inhale. Oxygen-containing air enters trachea from nasal cavity or oral cavity, then enters lungs, chest cavity expands, abdomen contracts and breathes; air is exchanged from lungs to trachea, then exhaled from nasal cavity or oral cavity, chest cavity contracts and abdomen relaxes.
2-2 Compared with inhaled gas, oxygen decreases, carbon dioxide and other gases increase, and chlorine remains unchanged.
2-2 Normal people breathe about 20 times per minute in a calm state. The heart beats about 80 times a minute.
2-2 Why does breathing accelerate during exercise? Because the human body needs to consume a lot of oxygen during exercise, it breathes more than usual, and thus exhales and inhales more gas than usual.
2-2 Oxygen needed by the human body enters the blood after being inhaled by the lungs, and then is transported to various parts of the body by the heart through blood vessels, and wastes such as carbon dioxide are collected and excreted.
2-2 Why does the heart beat faster during exercise? Because with the increase of physical activity, people need more oxygen, and their heart beats faster gradually, thus delivering more blood.
2-3 Regular exercise will improve our breathing ability, increase our vital capacity and get more oxygen.
2-3 vital capacity refers to the total amount of gas you try to inhale and then try to exhale.
2-3 We breathe all the time, and with the increase of exercise, the number of breaths per minute will also increase.
Besides breathing, diet is another important activity for us to get energy from the outside world.
2-4 According to people's living habits, food can be divided into grains, leeks, meat, dairy products, fruits and condiments.
2-4 According to the food source, it can be divided into plant food and animal food; According to the way food is eaten, it can be divided into raw food and cooked food; According to its importance, food can be divided into staple food and non-staple food. In addition, there are other classification methods.
2-4 The staple foods we often eat are rice, noodles and steamed bread. Non-staple foods include meat, eggs and milk. The cold dishes we often eat in summer include cucumber, vermicelli, vermicelli and other foods, which are classified as plant foods according to food sources.
2-4 Plant foods include grains, fruits and vegetables; Animal foods include milk, dairy products, eggs and meat.
2-5 All the nutrients needed by human body are obtained from food.
2-5 The nutrients in food are usually divided into protein, sugar, fat, vitamins, inorganic salts and water.
2-5 starch is a food rich in sugar. Foods such as fat and sesame are rich in fat.
2-5 protein is the main component of human muscles, viscera, hair, nails and blood, which supports growth and development. Rich in eggs
White foods include: soybeans, beef, fish, eggs, pure milk, pistachios and so on. Protein smells burnt after burning.
2-5 Fat and sugar are the main sources of human energy, and our body can store a lot of fat and sugar. Foods rich in fat are: cooking oil, peanuts, walnuts, pork, chocolate and so on. Foods rich in sugar are: rice, noodles, juice drinks, cooking starch, potatoes and so on.
2-5 Vitamins and minerals have the function of regulating body functions, and there are many kinds, which are indispensable for us to keep healthy. Water spinach and fruits are rich in vitamins and minerals, including carrots, tomatoes, green beans, pumpkins, cauliflower and celery. Salt is a kind of food rich in minerals, and water is also the most basic nutrient for human body. The nutrition the human body needs comes from food.
2-5 If the food is squeezed on the white paper and oil stains are left on the white paper, it means that this food contains fat. Dropping iodine on food is to test whether the food contains starch, and the place where iodine is dropped turns blue, indicating that this food contains starch.
2-5 To know whether the food contains protein, vitamins, minerals and other nutrients, you can look at the label or check the ingredients.
2-5 There are many kinds of food with rich nutrition. Only by maintaining reasonable nutrition can we keep healthy.
2-5 people need nutrition for their growth and activities, and nutrition is obtained from food.
2-6 No food contains all the nutrients the human body needs, so we need to match the diet to ensure adequate nutrition.
2-6 Dietary nutrition should be diversified and kept in a reasonable amount.
2-6 dietary nutrition collocation principle: meat and vegetable collocation; Coarse and fine grain collocation; A variety of collocation; Eat proper fresh fruits and vegetables every day; The momentum is relatively large. Need to eat more sugary food: some peeling between fingers, need to eat more foods containing vitamins.
Only balanced nutrition can guarantee our normal life and growth.
2-6 The status and proportion of various foods in balanced nutrition are different.
2-6 When finger peeling and oral ulcer occur, you need to eat more foods rich in vitamins.
2-6 Cereals and fatty foods contain sugar and fat, which can provide us with energy.
2-6 Dairy products, beans, fish, shrimp and eggs contain protein which can support our growth and development.
2-6 Vegetables and fruits contain vitamins and minerals, which can keep us healthy.
2-6 It is a good eating habit to get balanced nutrition from food, without partial eclipse or picky eaters. If the nutrition is not balanced, it will affect your health.
2-7 Digestive organs can convert food into nutrients and energy that we can absorb. This process is called digestion. Oral cavity is one of the digestive organs of human body.
2-7 Oral cavity is the place where food digestion begins, which is completed by teeth, tongue and saliva. Teeth are divided into incisors (8 teeth), canines (4 teeth) and molars (20 teeth) according to their shapes. 0
2-7 front teeth: used for cutting food; White teeth: used for chewing food; Dog teeth: used for chopping food.
2-7 The reason why the elderly often say "chew slowly" is that teeth grind food to facilitate the digestion of big food in the body.
2-7 teeth are not pregnant, chemistry will be affected, and the movement of the whole body will also be affected. Pareto diagram of incisor flow distribution
2-7 teeth are important digestive tools for our body. Different shapes of teeth play different roles in the process of digesting food. Protecting teeth is of great significance to our life-long health.
2-8 The digestive organs of human body mainly include mouth, esophagus, stomach, small intestine and large intestine. Food is transported from the esophagus to the stomach, where it is further ground and decomposed and absorbed in the small intestine.
2-8 Oral cavity: preliminary digestion of food: esophageal features: smooth and straight, function: conveying food to the stomach: setting features: muscular, acid in the stomach. Function: Turn food into chyme: Small intestine features: 5-7 meters long, with a large amount of digestive juice. Function: The main place for digestion and absorption: large intestine: storing food residues and absorbing a small amount of water.
2-8 Every digestive organ in the human body has its own function and needs our care.
2-8 Travel route of gourmet: gourmet >; Oral esophagus >; Stomach and small intestine, isolated large intestine
2-8 The human body can be divided into: exercise system, digestive system, blood circulation system, respiratory system, etc.
Motor system: (bones, joints, muscles)
Digestive system: (mouth, esophagus, stomach, small intestine, large intestine)
Blood circulation system: (heart, blood vessels)
Respiratory system: (nasal cavity, trachea, bronchus, lungs)
The movement and intensity of scientific knowledge points in the first volume of the fourth grade
3- 1 All objects have a vertical downward force, and this force is gravity.
3- 1 gravity can pull objects on the earth's surface to the ground. When the apples on the tree fall, the ball thrown into the air will always fall back to the ground, and the child will slide down the slide and the water will flow downwards. ...........................................................................................................................................
3- 1 In the experiment of the relationship between the moving speed of the car and the pulling force, the pulling force is expressed by the number of washers.
3- 1 provides power to start the car, and there is resistance to stop the moving car.
When the gas in the 3-2 balloon is ejected, it will produce a thrust opposite to the ejection direction. This force is called recoil.
3-2 inflatable balloons have energy and can generate electricity when blown.
3-2 jet planes and rockets are all moved by the recoil generated by jet engines.
3-3 Objects like rubber bands can easily change shape when subjected to external force. When their shapes change, they will produce a force to restore their original shapes, which is called elasticity.
3-3 For a car powered by a rubber band, the more times the rubber band is wound, the faster it travels and the farther it travels; The fewer times the rubber band is wound, the slower it goes and the closer it gets.
3-4 When learning sports and force, it is often necessary to know the magnitude of force, and the spring dynamometer is a tool to measure the magnitude of force.
3-4 spring dynamometer is made by using the characteristics that the greater the tension, the longer the spring and the greater the indicated value. The spring scale consists of five parts: (lifting ring), (pointer), (scale plate), (hook) and (elastic spring).
The unit of 3-4 force is Newton, which is abbreviated as "cow" and represented by the symbol "n". 1 Newton is approximately equal to 100 gram force. It is named after the famous British physicist Newton.
3-4 When using spring dynamometer to measure gravity, attention should be paid to:
(1) Pick up the dynamometer and check whether the pointer is in the "0" position:
(2) when reading, the line of sight is flush with the pointer:
(3) The measured force shall not exceed the maximum value marked on the dynamometer scale.
3-4 springboard, fitness ball, pole and sponge pad, trampoline, etc. All use the elasticity of objects.
3-5 When an object moves on the surface of another object, the contact surface of the two objects will be rubbed, and the moving object will be subjected to a force that hinders the movement. This force is called friction.
3-5 There are two ways for an object to move on the surface of another object: sliding and rolling. Sliding friction is much larger than rolling friction.
3-5 We use a dynamometer to pull an object in the horizontal direction, and the force that can just make this object move is the friction it receives.
3-5 The contact surface between objects is smooth, and the friction is smaller: the contact surface between objects is rough. The greater the friction, the heavier the object, and the greater the friction when moving: the lighter the object, the smaller the friction.
3-5 places where friction is needed on bicycles: front and rear tires, pedal surfaces, bicycle rubber and handlebars are patterned; Where friction is not needed: front axle, middle axle, rear axle, pedal axle, large and small gears and chains.
3-6 flying bullets pierced the object, the football kicked broke the glass, and the whistling wind uprooted the tree. The swift river drives the water wheel to turn ... they all have energy.
3-6 Any object needs energy to work. Without energy, there would be no movement and change in nature. There will be no life.
There are various forms of energy in our daily life, such as moving cars, glowing light bulbs, burning candles and stretching rubber bands. Energy is also stored in fuel, food and some chemicals.
Fourth grade, the first volume of science, the whole volume of knowledge related articles:
★ Review materials of the first volume of science in the fourth grade of primary school by Education Press.
★ People's Education Edition, Grade Four, Volume One, Scientific Review Materials
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★ Summary of knowledge points in the first volume of fourth grade mathematics
★ Review materials at the end of the fourth grade science.
★ Review materials of science units in the first volume of the fourth grade of Jiangsu Education Edition.
★ Scientific review materials of the first volume of the fourth grade of Jiangsu Education Edition.
★ People's Education Edition Grade Four Volume I Science Final Review Plan (2)
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★ People's Education Edition, Grade Four, Volume One, Scientific Review Questions
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