The Child Doesn’t Know Anything When Asking Questions? Collect These Common Knowledge About Primary School Students’ Life Quickly

In their daily study and life, children always come up with all kinds of interesting questions.

From the mysteries contained in the human body to the phenomena presented by nature, from environmental protection to the principles of science, these seem to be quite simple common sense, but in fact they all hide extremely profound knowledge.

Knowing these knowledge can not only expand their knowledge, but also help children better understand everything in the world and cultivate a scientific way of thinking.

Each of the following carefully selected common sense questions and answers has been scientifically verified and is true and reliable. Parents can tell their children with peace of mind.

Parachute speed is independent of material

Many people think that the speed of parachute descent is related to the fabric of the umbrella, but this is not actually the case.

The area of ​​the umbrella surface affects the descent speed of the parachute. Air resistance also affects the descent speed of the parachute. The weight of the falling object also determines the descent speed of the parachute.

As long as the umbrella surface is the same size, whether it is silk or nylon, the falling speed is basically the same.

Some scientists, after many experiments, have confirmed that under the same conditions, there is no obvious difference in the speed of descent of parachutes made of different materials.

This is because air resistance is mainly related to the projected area of ​​the umbrella surface, not the characteristics of the material itself.

Forty years of research on chimpanzee behavior

Jane Goodall, the famous British zoologist, spent 40 years studying the behavioral patterns of chimpanzees in depth.

During long-term observations in Gombe Stream National Park in Africa, she discovered that chimpanzees have the ability to use tools, have social hierarchies, and can even express their inner emotions.

This groundbreaking research completely and completely reversed human understanding of animal behavior.

With patient and meticulous observation, Jenny recorded the precious footage of chimpanzees "fishing" for termites with grass stems. This footage proved that animals also have the ability to make and use tools. This discovery prompted the scientific community to redefine the boundaries between humans and animals.

Planting green manure to enhance soil fertility

If you want to make the land more fertile, the most environmentally friendly and effective way is to Planting green manure .

For example, when they grow to corresponding stages, green manure crops such as milkvetch, alfalfa, and sesbania can be rolled directly into the soil. After they rot, they can increase the organic matter in the soil and improve the soil structure.

The root system of green manure can loosen the soil, fix nitrogen in the air, and provide nutrients for subsequent crops.

Compared with chemical fertilizers, green manure does not cause pollution, does not damage soil ecology, and can reduce soil erosion.

When farmers plant green manure during the fallow period, when they plant crops next year, the yield will be significantly improved, and the quality will also be significantly improved.

The human skeleton is called the skeletal system

In the human body, there are 206 bones. These bones are connected to each other and together form the supporting structure of the human body, and this supporting structure is called the skeletal system.

The support of the body and the maintenance of the body's shape depend on the bones, and the protection of the brain, heart, lungs and other important organs are also inseparable from the bones.

The skull protects the brain like a helmet, and the ribs protect the heart and lungs like a cage.

Bones are also the body's calcium reservoir, storing large amounts of calcium and releasing it into the blood when needed.

At the same time, the red bone marrow in the bones is responsible for producing blood cells. Because of this, it can be said that the skeletal system is very critical to the human body.

The younger you are, the faster you breathe

Under normal circumstances, a person's breathing rate is closely related to his or her age.

The younger you are, the faster your respiratory rate is.

In one minute, the number of breathing times of a newborn is roughly in the range of 40 to 44 times, the number of breathing times of an infant is about 30 times, the number of breathing times of a young child is about 24 times, and the number of breathing times of an adult drops to about 16 to 20 times.

The reason for this is that children have a strong metabolism and require more oxygen. However, their lung capacity is relatively small, so they can only meet the body's demand for oxygen by accelerating their breathing rate.

As we age, our lungs mature and form, allowing more gas to be exchanged with each breath, so the breathing rate naturally slows down.

The magnetic force of electromagnets cannot only rely on adding batteries

want to increase electromagnet Magnetism, simply adding batteries may not work.

The magnetic force of an electromagnet depends on and is determined by three factors: the number of turns of the coil, the size of the current, and whether there is an iron core.

Increasing the voltage and making the current larger can be achieved by adding more batteries. However, if the coil is too thin, once the current becomes too large, the wire will be burned.

It would be better to do the following: increase the number of turns in the coil, use thicker wires, add an iron core, or increase the voltage appropriately.

Only by comprehensively adjusting these factors can the magnetism be safely and effectively enhanced.

Blindly adding batteries may cause danger.

The sound stops as the vibration disappears

Sound is caused by objects vibration Everyone knows this principle.

But many people don't know that once the object stops vibrating, the sound will disappear immediately.

When you beat the drum, the drum head will vibrate and make a sound. If you press the drum head with your hand, the vibration will stop, and the sound will disappear immediately.

When you pluck the strings of a guitar, the strings vibrate to make a sound. When you hold down the strings to stop vibrating, the sound stops.

This shows that the existence of sound completely depends on vibration. The moment the vibration disappears, the sound ceases to exist. There is no so-called physical phenomenon of "reverberation around the beam". That is the echo.

At 11 a.m. the shadow is shorter than in the morning

At 8 o'clock in the morning, Xiao Ming measured the tree and found that the length of the tree's shadow was 6 meters. At 11 o'clock in the morning, he went to measure again and found that the shadow did not develop in the direction of lengthening, but in the direction of shortening.

This is caused by the changing position of the sun in the sky.

In the morning, the sun shines obliquely, making the shadow appear very long. Then, as time goes on, the sun continues to rise gradually, the light becomes more vertical, and the shadow gradually becomes shorter.

At noon, the shadow is the shortest, and in the afternoon the sun sets and the shadow begins to grow longer again.

Therefore, the shadow at 11 a.m. will inevitably be shorter than the shadow at 8 a.m. This is due to the natural law caused by the rotation of the earth.

Increase the triangular structure of the beam to make it more stable

Unstable structures can be increased by erecting beams triangle structure to become stable.

Triangles are stable. Once the three sides are fixed, the shape is difficult to change.

For example, the iron frame at the school, the trusses on the bridge, and the girder on the roof all use this principle.

The quadrilateral is easy to deform, and the pentagon is also easy to deform. However, adding a diagonal beam to divide it into several triangles makes the entire structure much stronger.

In daily life, we often see ladders, scaffolding, and high-voltage line towers, all of which make extensive use of triangular structures to ensure safety.

The earth’s fresh water is not inexhaustible

Many people think that there is a lot of fresh water on the earth and cannot be used up. This is a very wrong idea.

Although more than 70% of the earth is water, fresh water only accounts for about 2.5%, and most of it is stored in glaciers and ice caps. The water in rivers and lakes that humans can directly use only accounts for about 0.3% of the total fresh water.

Coupled with serious water pollution and waste, many areas are already severely short of water.

Therefore, fresh water is by no means always inexhaustible. Everyone must save water and protect water sources. Otherwise, there will be no water available in the future.

The seven-color disc turns white after rotating

Seven colors, red, orange, yellow, green, blue, indigo, and violet, are painted on the disk. When the disk rotates rapidly, these colors will be mixed with each other, making it impossible to distinguish clearly, and it will almost appear white.

Due to the persistence of vision characteristics of the human eye, it will happen that when the rotation of the disk reaches a fast enough level, each color has not disappeared in the human eye, and then the next color has arrived, so that the brain will mix them together.

Newton did this experiment and proved that white light is composed of seven colors of light.

This principle is applied to color TVs. Various colors are mixed through the three primary colors of red, green and blue. It is also applied to computer screens.

The glass from which the water was poured is not empty

Pour out the water in the cup. There is nothing in the cup.

Although you can’t see it, the cup is full Air .

Air is a real substance that is composed of a mixture of nitrogen, oxygen, carbon dioxide and other different gases.

Air has mass, takes up space, and can move.

If you put a cup upside down into water and the water can't get in, it's because the air is taking up space.

So strictly speaking, there is still air in the cup from which the water is poured out, not nothing.

This knowledge point can help children understand the difference between "matter" and "vacuum".

The gas on the pot lid is not water vapor

When cooking rice, when you open the pot and see the white "gas", it is not water vapor .

Water vapor is colorless and transparent and cannot be seen at all.

The phenomenon that we can see as white gas is caused by water vapor in a high-temperature state encountering lower-temperature air, and then rapidly condensing, eventually forming a large number of extremely tiny water droplets, which are suspended in the air.

Just like the white mist you can see when breathing in winter, this is a condition where exhaled water vapor condenses when it encounters cold.

There is common sense that real vapor is invisible, but many adults have misunderstandings in this regard, so this is worth explaining clearly to children.

Industrial wastewater and domestic sewage are the main sources of pollution

The main reasons for the deterioration and pollution of water quality in our country's rivers and lakes are wastewater produced by industrial production processes and sewage discharged from daily life.

Wastewater discharged from factories contains heavy metals, oil, and chemicals. Direct discharge without treatment will cause serious pollution to water bodies.

Domestic sewage containing detergents mixed with feces and ingredients from kitchen waste is rich in nitrogen and phosphorus, which will cause eutrophication of the water body and allow algae to grow wildly.

Excessive use of chemical fertilizers and pesticides in agriculture will also cause pollution when rainwater flows into rivers and lakes.

To protect water resources, these pollution sources must be controlled from the source, and every link must not be relaxed.

Red tide causes death of fish and shrimps

occur red tide There are several main reasons why a large number of fish and shrimps die.

There are a large number of plankton in the sea. These plankton are in a state of explosive reproduction. They float on the sea surface. Their behavior not only consumes all the oxygen in the water, but also acts like a cover, preventing oxygen from the air from entering the water body.

Fish and shrimp in the water will suffocate due to lack of oxygen.

At the same time, red tide organisms will secrete mucus, which will stick to the gills of fish, shrimp, and shellfish, thereby hindering their breathing, and eventually causing them to suffocate and die.

After red tide organisms die and decompose, they will also produce toxic substances, further poisoning marine life.

Therefore, red tides cause great damage to marine ecology.

Red tide toxins harm human health

Red tides not only harm marine life, but also directly threaten human health.

If humans eat fish and shellfish contaminated by red tide, poisoning will occur, and in severe cases, even death.

Some algae present in red tides can produce neurotoxins, hepatotoxins, etc. After shellfish filter-feed these algae, the toxins become enriched in their bodies, and humans will be poisoned if they eat these shellfish.

Symptoms of poisoning include vomiting, diarrhea, dizziness, muscle paralysis, and in severe cases, respiratory failure.

Therefore, during the period when red tide breaks out, you must not pick up shellfish near the seaside, and you must also choose formal channels when purchasing seafood.

Brushing teeth without turning off the water wastes more than three liters

If the flow of mouthwash continues while brushing your teeth, more than 3 liters of water will be wasted each time you brush your teeth. These 3 liters of water are equivalent to 3 kilograms.

Many people are used to turning on the faucet and letting the water flow when brushing their teeth, which doesn't feel like much.

However, after calculation, we can know that normal brushing time usually takes 2 to 3 minutes, and the faucet will flow out 6 to 8 liters of water every minute. In this way, brushing your teeth at one time will easily waste more than ten liters of water.

When brushing your teeth with water in a cup, a cup of water is enough.

If all 1.4 billion people in the country changed this habit, the amount of water saved every day would be staggering.

Saving water starts with this small habit. Teach your children to turn off the faucet when brushing their teeth.

Two effective ways to reduce plastic waste

If you want to effectively reduce plastic waste, you can start from two aspects.

First of all, avoid purchasing as much as possible and avoid the use of disposable plastic products. For example, when going to the supermarket, bring your own cloth bags and abandon the use of plastic bags; when drinking water, bring your own water cup and do not buy bottled water; for takeout orders, choose the "no tableware required" option.

Secondly, it is necessary to reuse, avoid using disposable items, wash plastic bags and reuse them, and turn plastic bottles into flower pots or storage boxes.

It takes hundreds of years for plastics to degrade in nature, so garbage siege has become a serious problem.

Using one less plastic bag per person can greatly reduce the pressure on the environment.

The main causes of soil desertification are human activities and climate change

soil becomes desert The main reason is Human activities and climate change .

Grassland is degraded due to overgrazing, vegetation is destroyed due to over-cultivation, and soil erosion is caused by deforestation. Under these circumstances, human activities have caused the land to lose protection.

As global climate warming increases, precipitation in arid areas decreases, evaporation becomes more intense, and the soil becomes increasingly dry.

Even if the topsoil is not anchored by vegetation, once it encounters strong winds, those fine soil particles will be swept away, leaving coarse gravel behind, eventually forming a desert.

To prevent and control desertification, we need to return farmland to forests, grazing animals rationally, and saving water, because man and nature are a community with a shared future.

Drug residues enter food through feed and drugs

In meat, eggs, fish drug residue , mainly through two ways.

First of all, there is a situation where contaminated feed is used to feed livestock, poultry, and fish. That feed may contain pesticide residues, heavy metals, and mycotoxins.

The second point is that when carrying out disease prevention and treatment operations, drugs such as antibiotics are used. Farmers add drugs to the feed for the purpose of preventing diseases or promoting animal growth, and these drugs added to the feed will remain inside the animals' bodies.

When people eat these meat, eggs and fish, the medicine will enter the human body. If it accumulates for a long time, it may cause problems such as drug resistance and allergies.

Therefore, it is important to choose food from formal channels.

These common sense of life, involving the fields of physics, biology, chemistry, environment and many other fields, have been scientifically verified and are real knowledge.

Learning them will not only enable children to gain stronger confidence in class, but also have the potential to cultivate habits such as observation and thinking.

Parents can discuss with their children, look for these phenomena in life, and combine book knowledge with actual situations, so that learning will become more interesting.