Children's sports knowledge 1. Choose the right exercise. Physical exercise (active and passive exercise) is the basic means of children's physical education. There are many sports to choose from, including running, jumping, throwing and pressing. Hide and seek; Dance, slides, swings and other games; Outing, racket ball, skipping rope, riding a children's car, swimming, gymnastics and other sports. All these exercises are aimed at strengthening physical fitness and entertaining body and mind. Common sense 2 There are many ways to choose sports, and different sports can produce different exercise effects. For example, to improve speed, you can choose to run and ride a children's car; To enhance endurance, you can choose long-distance running games, swimming, outing, skipping rope and other sports; To increase strength, you can choose jumping, throwing and other exercises; To improve your sensitivity and coordination, you can choose to dance, swing, racket ball and other games; To improve flexibility, you can choose gymnastics, pressing and other exercises. Common sense 3 Children's sports should have scientific guidance and reasonable amount of exercise. The formulation and selection of basic sports must master the amount of exercise scientifically. Too little exercise has little effect on physical exercise. If you exercise too much and have no rhythm, your body will also be adversely affected.
2. Children's sports tips
Children's sports knowledge 1. Choose the right exercise. Physical exercise (active and passive exercise) is the basic means of children's physical education. There are many sports to choose from, including running, jumping, throwing and pressing. Hide and seek; Dance, slides, swings and other games; Outing, racket ball, skipping rope, riding a children's car, swimming, gymnastics and other sports.
All these exercises are aimed at strengthening physical fitness and entertaining body and mind. Common sense 2 There are many ways to choose sports, and different sports can produce different exercise effects.
For example, to improve speed, you can choose to run and ride a children's car; To enhance endurance, you can choose long-distance running games, swimming, outing, skipping rope and other sports; To increase strength, you can choose jumping, throwing and other exercises; To improve your sensitivity and coordination, you can choose to dance, swing, racket ball and other games; To improve flexibility, you can choose gymnastics, pressing and other exercises. Common sense 3 Children's sports should have scientific guidance and reasonable amount of exercise.
The formulation and selection of basic sports must master the amount of exercise scientifically. Too little exercise has little effect on physical exercise. If you exercise too much and have no rhythm, your body will also be adversely affected.
3. Children's health tips
Eggs are a kind of nutritious food. An egg weighs about 50 grams, contains 7 grams of protein and 6 grams of fat, and generates 82 kilocalories. The amino acid ratio of egg protein is very suitable for human physiological needs, easy to be absorbed by human body, with a utilization rate of over 98% and high nutritional value. Eggs are rich in calcium, phosphorus, iron, vitamins A and B, as well as various vitamins and trace elements necessary for human body. They are good supplements for children, the elderly, pregnant women, patients with hepatitis, tuberculosis and anemia, and patients in recovery after surgery.
Although eggs are good, we should pay attention to science in consumption. According to a recent survey, among some urban workers, some young people engaged in mental or light manual labor eat 5-6 eggs a day to increase nutrition; Some primary and middle school students eat 3 eggs for breakfast and 1~2 eggs for lunch and dinner every day. In some rural areas, pregnant women eat 10~ 15 capsules a day, but actually eat 300~450 capsules a month. They think: "eggs are nutritious, so eat more to supplement your body." In fact, eating too much will bring some bad effects to the body.
First of all, eggs contain a lot of cholesterol. Eating too many eggs will greatly increase the intake of cholesterol, leading to high cholesterol content in the blood, causing atherosclerosis and cardiovascular and cerebrovascular diseases. Take lying-in women as an example, one egg contains about 250 mg of cholesterol, and 10 egg contains about 2500 mg of cholesterol. This amount is nearly 10 times the normal intake. In addition, the fat rich in eggs belongs to saturated fatty acids. Excessive intake will inevitably lead to a sharp rise in serum cholesterol and promote the occurrence of atherosclerosis and cardiovascular and cerebrovascular diseases.
Secondly, eating too many eggs can easily lead to overnutrition and obesity. During postpartum lactation, women generally need about 2,800 ~ 3,000 kcal per day, and protein needs about 90g. For example, eating 10 eggs every day is equivalent to eating 70g of protein and 60g of fat, which is about 82 0 kilocalories. In addition, lactating mothers should eat a certain amount of staple food, such as chicken, fish, meat, bean products, vegetables and fruits. The daily calorie intake can be achieved. This far exceeds their daily actual nutritional needs, resulting in overnutrition, which will lead to the accumulation of excess fat in the body and the formation of obesity.
Eating too many eggs will also cause the imbalance of nutrients in the body and affect health. Our daily diet consists of a variety of foods. A reasonable and balanced diet needs all kinds of nutrients needed by the human body, and all kinds of nutrients should have an appropriate proportion in the diet. Because all kinds of nutrients play a coordinating and restricting role in the body. Only in this way can the body develop normally and stay healthy. No matter what kind of food, no matter how high its nutritional value, it is impossible to contain all the nutrients needed by the human body. Eating a food for a long time will make some nutrients surplus and others insufficient. Eggs are no exception. Eggs themselves can't supply all the nutrients needed by the human body. For example, they contain no carbohydrates, and the content of vitamin C is almost zero. Therefore, eating too many eggs will inevitably reduce the intake of other foods and make the intake of various nutrients unbalanced. Over time, it is easy to cause related diseases due to the lack or excess of other nutrients.
Eating too many eggs will also increase the burden on the liver and kidneys. Eating 1~2 eggs a day can meet the eight essential amino acids needed by the human body. Because the body no longer needs it, it will not be absorbed and utilized, but will be converted into fat to accumulate in the body or wasted as heat. Moreover, if you eat too many eggs, protein's catabolic products will increase the burden on the liver, and a large amount of nitrogen-containing waste produced after metabolism in the body will be excreted through the kidneys, which will directly increase the burden on the kidneys, so eating too many eggs is not good for the liver and kidneys.
So, how many eggs should a person eat every day? From the point of view of nutrition, in order to ensure a balanced diet, meet the needs of the body, and not be overnourished, under normal circumstances, it is better for the elderly to eat 1~2 capsules a day. For young and middle-aged people, it is more appropriate to eat 2 eggs a day if they are engaged in mental or light physical labor; Those who are engaged in heavy physical labor and take more nutrients can eat 2~3 eggs a day; Teenagers and children can take 2~3 capsules a day because of their long body and fast metabolism. Pregnant women, lying-in women, weak nursing mothers and patients recovering from major surgery can eat 3-4 eggs a day, but not more, because they need to increase the quality of protein.
4. What are the common knowledge of children's health?
Basic knowledge of primary school students' health
1, wash your hands before and after meals;
2, do three diligence: diligent bathing, diligent haircut, and diligent dressing;
3, diligently cut nails;
4, pay attention to reading and writing hygiene: the eyes are one foot away from the book, the body is one punch away from the table, and the hand is one inch away from the nib;
5. Wash your hands frequently anytime and anywhere;
6. Pay attention to eye hygiene: don't read in strong light, don't read in a walking car, don't read while lying down, and don't rub your eyes with dirty hands;
7. Do not eat unsanitary food, do not eat unwashed food, and do not drink raw water;
8. Wash your face in the morning and evening, wash your face with running water, and don't use towels, washbasins and other items with others;
9. Brush your teeth in the morning and evening and rinse your mouth after meals;
10, insist on proper physical exercise every day, in order to enhance physical fitness and maintain good and abundant energy.
Eye hygiene of primary school students
Pay attention to eye hygiene and achieve "two wants and two don't"
(1) seconds:
(1) The reading and writing posture should be correct, and "one foot, one punch and one inch" should be maintained, that is, the eyes should be one foot away from the book, the body should punch from the table edge, and the fingers should be one inch away from the pen tip;
(2) Take a rest after reading and writing for an hour or so, or look far away for a while.
(2) Don't: ① Don't read or write in dim light or direct sunlight;
② Don't read while lying down, walking or riding a bike.
How to pay attention to hygiene when watching TV?
① Watch TV for no more than 2 hours at a time. After watching TV 1 hour continuously, get up and exercise for 5- 10 minutes.
② The viewer should be more than 2 meters away from the TV screen;
③ The height of the TV set should be consistent with the eye height of the viewer when sitting;
④ It is best to turn on 3-8 watts of small lights indoors to reduce the sharp contrast between the screen and the surrounding darkness, which is conducive to avoiding eye fatigue.
How to prevent myopia?
① Pay attention to eye hygiene;
② Insist on doing eye exercises;
③ Combination of work and rest and adequate sleep;
④ Pay attention to nutrition, strengthen exercise and enhance physical fitness;
⑤ Check your eyesight regularly, and correct the decline in time to prevent myopia from deepening.
How to protect teeth?
1. The most important thing to protect your teeth is to brush your teeth and rinse your mouth correctly. Brush at least twice a day, preferably after each meal. Brushing teeth can remove dental plaque attached to teeth, because bacteria in dental plaque come into contact with food, which will produce acidic substances and lead to tooth decay. Brush your teeth unconditionally. At least rinse your mouth immediately after eating or eating acidic substances.
2. Pay attention to your diet. Food should be diversified, but eat less foods rich in sugar (especially monosaccharides). Because these foods will produce acid in your mouth, the acid will stay in your mouth for a long time and will damage your teeth. Hard lollipops are especially harmful to children. Eating sugary snacks can also cause tooth decay, because most people don't brush their teeth after eating snacks. Starch snacks, such as potato chips, stick to your teeth.
It is best to floss your teeth once a day. Flossing can remove food and dental plaque left between teeth. If dental plaque remains between teeth, it will form tartar and must be removed by the dentist.
See a dentist every six months. It is very important to have regular checkups and professional tooth cleaning.
5. What are the scientific health common sense?
1. Get up without overlapping. The human body itself is also a pollution source.
In a night's sleep, human skin will emit a lot of water vapor, making the quilt moist to varying degrees. There are 145 kinds of chemicals excreted by human breath and pores all over the body, and 15 1 kind of chemicals evaporated by sweat.
The quilt absorbs or absorbs moisture and gas. If you don't let it out, it will overlap immediately after getting up, which will easily make the quilt wet and polluted by chemicals. 2. Common sense of life. Fruits often rot, so people dig out the rotten parts with knives and eat the rest without rotting.
Actually, this is not right. Because the rest is not rotten, but most of them have been eroded by harmful substances produced in the process of microbial metabolism, especially the reproduction of fungi on fruits is accelerated, and some fungi will produce toxic substances during the reproduction process.
These toxic substances can spread from the rotten part to the non-rotten part through the juice, so that the non-rotten part contains the same microbial metabolites as the rotten part, especially mycotoxins, some of which can cause cancer. 3. People who don't eat breakfast usually eat irregularly, are prone to fatigue and dizziness, which will lead to malnutrition, anemia, decreased resistance, pancreas and gallstones over time.
4. Loosening the belt after meals can reduce the intra-abdominal pressure, increase the activity of digestive organs and the load of ligaments, thus promoting the increase of intestinal peristalsis, prone to intestinal volvulus, abdominal distension, abdominal pain, vomiting, and prone to diseases such as gastroptosis. Sleeping after a meal will make the blood in the brain flow to the stomach. With the decrease of blood pressure, the oxygen supply to the brain will also decrease, which will lead to extreme fatigue after meals and easily lead to heartburn, indigestion and obesity.
If the blood supply is insufficient, you will fall asleep after meals. This motionless state can easily lead to a stroke. 6. Being full can easily lead to memory loss, slow thinking, inattention and weakened adaptability.
Often over-satiated, especially over-satiated dinner, due to excessive intake of calories, will make the body fat excess, blood lipids increase, leading to cerebral atherosclerosis. It also causes a substance called "fibroblast growth factor" to grow tens of thousands of times in the brain. This is a protein that promotes arteriosclerosis.
The result of cerebral arteriosclerosis will lead to hypoxia and lack of nutrition in the brain, thus affecting the metabolism of brain cells. Often full, it can also induce gallstones, cholecystitis, diabetes and other diseases, which will make people aging before they get old and shorten their life span.
7. More and more evidence shows that the longer the hobby of eating sugar on an empty stomach, the more serious the damage to protein absorption. Because protein is the foundation of life activities, eating sugar on an empty stomach for a long time will affect all kinds of normal functions of the human body, making the human body weak and shortening its life span.
8. Eating too salty food sodium stays in the human body, which is easy to form or aggravate high blood pressure and heart disease. 9. Grow a beard and absorb harmful substances.
When people inhale, harmful substances adsorbed on their beards may be inhaled into the respiratory tract. Quantitative analysis of the air composition inhaled by bearded people shows that the inhaled air contains dozens of harmful substances, including carcinogens such as phenol, toluene, acetone and isoprene, and the air pollution index inhaled by bearded people is 4. Twice as much as ordinary air.
If you have a beard and a moustache on your chin, the pollution index can be as high as 7.2 times. Coupled with smoking and other factors, the pollution index will be as high as 50 times that of ordinary air.
10. Crossing your legs will cause poor blood flow in your legs and affect your health. If you are a patient with venous tumor, arthritis, neuralgia and venous thrombosis, crossing your legs will make your condition worse.
Especially people with long legs or pregnant women, it is easy to get venous thrombosis. 1 1. Blinking and rubbing eyes are prone to fishbone wrinkles.
Habitual eye use can also cause eye muscle fatigue, dizziness and headache. When rubbing your eyes, germs can infect your eyes from your hands, leading to inflammation, broken eyelashes or falling off.
12. Forced urination may cause acute cystitis, which is characterized by frequent urination, dysuria, small abdominal distension and pain. A research report released by American scientists pointed out that people who have the habit of holding their urine are five times more likely to develop bladder cancer than the average person.
When holding urine, the urine stored in the bladder cannot be discharged in time, resulting in artificial urinary retention. If you hold your urine regularly, your sphincter and detrusor will always be in a state of tension; If you hold your urine for too long, the amount of urine in your bladder will continue to increase, and the internal pressure will gradually increase. After a long time, symptoms of bladder neck obstruction will appear, leading to dysuria and obstruction, or urinary leakage and incontinence.
Urinary retention is also easy to cause complicated infection and stones, and will also affect renal function in severe cases. Supplement: 13. The average person will have temporary blurred vision after taking a nap at his desk. The reason is that the eyeball is compressed, causing corneal deformation and curvature change.
If you press your eyeball every day, the intraocular pressure will be too high, and if this continues, your vision will be damaged. 14. Sleeping on the stomach bends the spine and increases the pressure on muscles and ligaments, making people still unable to rest while sleeping.
In addition, it will increase the pressure on the chest, heart, lungs and face, leading to facial edema and bloodshot eyes after waking up. 15. If you don't wash your face before going to bed, the cosmetics left on your face will cause inflammation such as acne and pinholes, and it will also make your eyes inflamed and cause skin allergic reactions.
16. It is more important to brush your teeth before going to bed than after getting up. This is because the bacteria and residues left in the mouth and teeth have a strong corrosive effect on teeth and tooth age at night. 17. Sleeping late will inhibit the cerebral cortex for a long time, which will cause a certain degree of artificial brain dysfunction, lead to a decline in understanding and memory ability, and also reduce immune function, disrupt the biological rhythm of the body, make people lazy and inert, and at the same time, it is not good for muscles, joints and urinary system.
In addition, poor blood circulation and untimely systemic nutrition delivery will also affect metabolism. Because the doors and windows are closed at night to sleep, the indoor air is cloudy in the morning, and falling in love with the bed is easy to cause respiratory diseases such as flu and cough.
18. The hot water bath time is too long. Chloroform and trichloroethylene are easily volatile harmful substances in tap water. Because more chlorine gas comes into contact with air during ice bath, these two harmful substances are released in large quantities. The data show that only 25% chloroform and 40% trichloroethylene are released into the air if hot water bath is used. When bathing with hot water, the chloroform released into the air will reach 50%, and trichloroethylene will reach 80% C.
19. Gambling is harmful.
6. What are the common knowledge of children's health?
1. Educate children not to bring toys and sharp tools to the park, let alone put them in their mouth, nose and ears to avoid injury.
2. Educate children not to play with toys with their peers, let alone scratch, bite or hit their peers.
3. Go up and down the stairs to the right, don't slide down from the handrail of the stairs, and don't do dangerous actions such as climbing the window, tearing the window, jumping up the stairs, playing with the door, jumping off from a height, etc.
4. When going to public places for sightseeing, going out for a walk or outdoor activities, educate children to stay away from dangerous places such as transformers and construction sites, and listen to teachers (or adults) and don't leave the group casually. Tell the teacher if anything happens.
5. Educate children to obey the teacher's arrangement during sports or games, observe discipline, conduct activities in an orderly manner, and avoid chasing, running around and colliding with each other.
6. Explain and publicize safety knowledge to children, so that children can understand the dangers of playing with fire, electricity and water to prevent accidents.
7. Guide children to understand the purpose of fire hydrants and fire extinguishers, and know the safe passage exit of kindergartens; Educate children to form the habit of observing fire signs and evacuation instructions in public places; Know all kinds of alarm calls and know how to call the police.
The main contents of kindergarten safety education
8. After school in the afternoon, educate children to bring adults, don't run around by themselves, and don't stay in the kindergarten to prevent accidents.
9. Educate children to know their names, garden names, parents' names, work units, home addresses and telephone numbers, and they will express clearly how to protect themselves in an emergency.
10. Teach children not to trust strangers at will, not to walk with strangers privately, and not to let strangers touch their bodies. Tell children that only parents, doctors and nurses can touch their bodies. If a stranger wants to do this, he must flee as soon as possible.
1 1. Educate children not to lock their doors at home, and not to play with dangerous goods such as gas, fire, lighters, kettles, water dispensers and medicines.
12. Educate children not to cross the road without adult guidance. When crossing the road, you should obey the traffic rules, walk on the sidewalk, don't stay and play on the road, and walk on the right in the street.
13. Teach children not to open the door at will when they are alone at home. Don't open the door when they hear a knock at the door. You can say "My parents are not at home, please come back later" to prevent thieves from entering the house when adults are away.
14, when traveling or walking in the wild, don't pick flowers and fruits casually, catch insects, and don't put them in your mouth to prevent accidents.
7. Scientific fitness methods
Correct exercise+adequate rest+reasonable diet = muscle growth! ! ! ! It is best to fix the exercise time and arrange each exercise at the same time as far as possible, so as to develop good exercise habits and help the internal organs of the body form conditioned reflex.
Do not exercise one hour after meals and one hour before going to bed, otherwise it will affect digestion and sleep. The best physical time is generally between 15:00-20:00, which can be considered as the main exercise time.
Exercise time should be suitable for beginners and people with heavy workload at ordinary times, three times a week, each time 1- 1. Five hours, but every exercise should include all parts of the muscles.
People who insist on exercising every day can divide the muscle group into two parts and practice every other day to ensure effective muscle recovery. For example, practice your shoulders, abdomen and chest today and your back, arms and legs tomorrow.
The load depends on a person's physical strength. Generally speaking, the effective number of developed muscle mass is 8-12, at least not less than 8 times, which should be the best effort. Therefore, the load should be controlled at 70%-80% of the individual's maximum strength, that is, the most effective number of times to use this load is to do it with heavy load, not more than 5 times.
The most effective number of times to develop endurance and reduce fat is to do it 20 times with a small load, and even to lose fat in the waist and abdomen. Each movement needs to practice several groups, and each exercise movement needs to practice several groups, so that the muscles that are * * * enter the state and the muscle mass increases.
Generally, the number of large muscle groups can be more, and the number of small muscle groups can be less. Every movement of beginners should be three groups, not less than two groups. After a certain foundation, we should join three to five groups according to the growth degree of strength.
Rest time should not be too long. The rest time between exercises in each group should not be too long, generally between 40 seconds and 50 seconds, and the rest time for high-load and high-intensity exercises should not exceed 15 minutes. Too long rest time will affect the exercise effect.
Mastering the correct breathing method can help you concentrate your thoughts, coordinate your movements and lift more weight during exercise. General movements and small weightlifting are hard, breathing in when muscles contract and exhaling when they relax and recover.
When lifting weights or trying to lift the last few times, take a deep breath first, then hold your breath and do the lifting action, and then take a deep breath. Breathe through your mouth during exercise, do stretching exercise before exercise to prevent muscle ligament strain, and do relaxation exercise after training to help eliminate muscle tension and restore fatigue.
Each exercise can last for 30 minutes to 60 minutes (excluding warm-up and relaxation activities). The most common mistake middle-aged people make in sports is to fish for three days and dry the net for two days.
Such exercise is not good for health. The improvement of physical fitness and physical fitness by exercise depends on the accumulation of the reaction of exercise to human organs and metabolism to a certain extent.
You should exercise more than three times a week because: ● You only exercise 1 time a week. After every exercise, you will have muscle pain, and your body's reaction will disappear after two or three days. The next exercise is equal to starting from scratch, and there is no exercise accumulation effect.
People who exercise like this are always at the starting point. ● Exercise twice a week. After exercise, the pain and fatigue of the body will be alleviated, and the effect of exercise will accumulate a little, but it is not significant.
● Exercise three times a week, basically once every other day. Not only can the exercise effect be fully accumulated, but also the fatigue after exercise is very light. ● If the frequency is increased 4 or 5 times a week, the effect will be improved accordingly.
It is ideal to exercise 3~5 times a week. Of course, in the process of implementation, we can make some small or partial adjustments according to our own feelings in order to be more practical.
After implementing a stage, according to your own feedback, re-test your physical strength and adjust your exercise prescription to a new level.
8. Encyclopedia of first-year scientific knowledge
Small scientific knowledge
1. Rabbits beat the ground with their legs to send messages. Most of them beat the ground with their hind legs, which is a way for them to express their feelings to the female rabbits.
2. The biggest monkey in the world is a baboon and the smallest monkey is a bonobo.
3. The real name of "Four Elephants" is Elk, which is a rare animal in China.
4. Why does sorbet get angry?
The reason why sorbet bubbles is because there is a lot of invisible water vapor in the outside air. When it comes to cold sorbet, it will liquefy into droplets when it is cold. It seems that the sorbet is bubbling.
5. Why do sunflowers always face the sun?
Sunflower stems contain a wonderful auxin. This auxin is very afraid of light. When it is illuminated, it will go to the backlight side, and the cells on the backlight side will multiply rapidly. Therefore, the backlit side will grow faster than the bright side, which will bend the sunflower to light.
9. Primary school students' sports health knowledge
Pupils grow and develop rapidly, their bodies are immature, and their bones, muscles, internal organs and other organs are fragile, so we must not neglect maintenance. The content of physical education class in primary schools must be conducive to promoting the all-round development of students' bodies and effectively exercising and strengthening their physique.
First, choose the right venue.
At present, the general school sports venues are mostly cement, such as basketball courts and volleyball courts. In fact, the playground paved with cement asphalt is hard and elastic. Jumping in this site run for a long time is not only easy to cause trauma, but also causes chronic damage to the human body. Therefore, qualified schools should try to set up plastic venues. This kind of venue can protect students from injury, and schools without conditions try to keep soil venues and battlefields.
Second, ensure the safety of equipment.
The choice of equipment is very important for the safety of students. Schools should strive to complete equipment in accordance with the requirements of the new curriculum standards. If there is no supporting equipment for the time being due to conditions, teachers and students can be mobilized to make their own equipment, but health and safety factors must be considered. It is necessary to ensure that unqualified equipment is not used, and bad equipment cannot be used.
Third, matters needing attention in class
1. Reasonable selection of exercise load. The characteristics of physical education itself determine that physical exercise is the main feature, outdoor is the main place, and it is dynamic, which increases the difficulty of organizing teaching. If students use instruments improperly or have too much physiological load, they are prone to injury accidents.
2. Strengthen physical education class's safety awareness. Physical education class needs students' bodies to participate in activities directly, which is really unsafe and potentially dangerous. However, as long as we attach importance to maintenance education, organize classes well, conduct teaching correctly and scientifically, and strengthen maintenance measures, injury accidents can be avoided.
3. Safety begins with the teacher. As a qualified physical education teacher, the consciousness of saving should permeate every link of preparing lessons, attending classes and summarizing after class. When preparing lessons, we should fully consider all kinds of unsafe factors and eliminate them one by one through our own efforts. We should not only write lesson plans well, but also prepare teaching materials, students and venue equipment, ponder the technical essentials, action structure, key and difficult points, protection and help of teaching materials, and fully understand the students' situation, such as physical condition, hobbies, discipline habits, sports ability and so on.
4. Teaching should be rigorous. In the teaching process, teachers should impart correct knowledge, sensitive skills and skillful skills to students, adopt scientific teaching methods, so that students can understand and master the essentials of movements, make clear the technical specifications and conduct accurate drills. Teachers must also personally lead or guide students to do adequate preparatory activities and necessary special exercises.
5. Clothing can't be ignored. Teachers must have strict requirements on physical education class's dress, so that students can gradually develop good habits. For example, don't wear leather shoes, sandals and plastic shoes; Do not carry sharp tools, such as keys and knives.