The new classroom of science in the first volume of the fourth grade

The first volume exercise book of the fourth grade of science refers to the answer "Dissolution" unit 1. Water can dissolve some substances 1. Multiple choice questions: (1) C(2) A(3) D(4) A 2. Glass rods, iron shelves, funnels and beakers. 2。 How does a substance dissolve in water 1? (omitted) 2. ( 1) C(2) B(3) C(4) C(5) A 3。 Dissolution between liquids 1. (omitted) 2. ( 1) C(2) A(3) C 4。 The solubility of different substances in water is 1. (1) 18 (2) 6 (3) salt 2. (1) I found that the liquid in the syringe occasionally emits some small bubbles; (2) I found a lot of bubbles coming out of the liquid in the syringe; (3) I found that the small bubbles in the syringe disappeared again. 3. The bubbling liquids are sprite, Coca Cola and beer. 5。 Fast and slow dissolution 1. (1) Fast, slow and stirring; (2) fast, slow and split; (3) Fast, slow and heating. 2.( 1) ×(2) ×(3) √ (4) √ 6。 100 ml How many grams of salt can water dissolve 1? ( 1) B (2) A 2。 Research questions: experimental materials: water, beaker, etc. Research steps: (1) Pour 100 ml of cold water into a beaker; (2) Add 2g salt into the beaker and stir with chopsticks until it is dissolved. (3) Repeat the second step until the salt cannot be dissolved by water. (4) Add salt every time, and add up the weight of salt. Research results: A cup 100 ml of water can dissolve about 36 grams of salt (based on the actual data). 7。 Method of separating salt from water 1. Add some water, because water will dissolve salt. The more water, the more salt will be dissolved. (or: stir, so that stirring can accelerate dissolution) 2. Salt will be separated, because salt needs water to dissolve, and less water will produce more salt. 3. Multiple choice questions (1) C (2) A (3) C (4) C.4. The crystal particles of salt particles and concentrated brine are white in color and shape, with large particle size and small other units. Exercise 1. Multiple choice questions ( 1)B(2)C(3)C(4)C(5)B(6)B(7)B 2。 (1) √ (2) √ (3) × (4) √ (5) √ (6) √ (7) × (8) × 3. Water-soluble items: salt, sugar, soap, potassium permanganate, alcohol, honey, hand sanitizer and shampoo; Water-insoluble items: stone, flour, plastic, vegetable oil, mercury, glue. 4. mapping. From top to bottom: external flame, internal flame, flame core, wick, alcohol. Sound unit 1 listening to sound 1. (omitted), height, strength, distance, length, etc. 2. True or false. (1) √ (2) ×(3) √ (4) × 3. Multiple choice questions. (1) How does C (2) B (3) B 2 sound come about1? Record. The name of the object makes the object happen. My discovery is that gongs, drums, steel rulers, rubber bands, tables, water and water drops all vibrate when they make a sound. Vibration 2. Multiple choice questions ( 1) B(2) C(3) C 3。 True or false. (1) √ (2) √ (3) ×(4) √ (5) √ 3 Changes in sound 1. Fill in the blanks. (1) volume and decibel; (2) Pitch, Hertz 2. True or false. (1) √ (2) √ (3) × 3. Judgment. (1) high → low; (2) low → high; (3) Low → High 4 Explore the pitch change of ruler 1. (1) The length of the ruler sticking out of the desktop is long and the sound is low. Because long objects vibrate slowly, the sound is low. (2) High, Medium, Low and Down. (3) The longer the ruler sticks out of the desktop, the lower the sound. 2. multiple choice questions. (1) A(2) B(3) A 5 sound propagation 1. Multiple choice questions ( 1) B(2) A(3) A(4) C(5) C 2。 Short answer. "Listen to the sound on the ground" is to take advantage of the fact that the earth can spread sound. Soldiers can judge the number and distance of horses according to the change of the weight of hooves heard from the earth. 6 How do we hear the sound 1. Connect. Ear canal-transmits sound waves to the middle ear; Tympanic membrane-converts sound waves into vibration; Auditory ossicles-transmit vibrations to the inner ear; Cochlea-converting vibration into auditory signals; Auditory nerve-transmits auditory signals to the brain. 2. Experimental records. The vibration of the rubber membrane is the same as we guessed, but the actual observation shows that the sound above the rubber membrane is stronger, the sound above the rubber membrane is weaker and the vibration is obvious. The distance between the sounding point and the eardrum is equal, and the vibration is not obvious. The received sound is closer to the rubber membrane and the vibration is obvious. The sound received is the same and the vibration is not obvious. Our discovery 7 protects our hearing 1. (1) ×(2) √ (3) √ (4) √ (5) √ 2. Mapping. Shake it gently, add cotton to the sounding pot, wrap it in cotton cloth, shake it slowly, and so on. Unit exercise 1. Fill in the blanks. (1) Leaves, bugs, etc. Cars, bells, etc. (2) vocal cords and wings; (3) strong (big or loud) weak (small or light); (4) high and low; (5) Wave (or sound wave). 2. True or false. (1) √ (2) ×(3) √ (4) ×(5) × 3. Multiple choice questions. ( 1) A(2) C(3) C(4) B 4。 Contact. The sound you hear is high-when you pluck the rubber band hard, the drum surface vibrates quickly; when you pluck the ruler that is short from the desktop, the sound you hear is low-when you pluck the rubber band gently, the drum surface vibrates slowly; when you pluck the ruler that is long from the desktop, the sound you hear is strong-when you pluck the gong hard, the sound you hear is weak-when you gently knock the gong. High → low; Low → high. Reason: When knocking on the test tube, the vibrating objects are glass and water. The more water, the slower the vibration and the lower the sound. When blowing a test tube, the vibrating object is air. The more air, the slower the vibration and the lower the sound. Weather unit 1 We care about the weather. True or false. ( 1) √ (2) ×(3) √ (4) √ 。 2. Fill in the form. Heavy rain, moderate rain and rainstorm; Sunny, cool, sunny to cloudy; Light snow, heavy snow, medium snow. 3. description. It is sunny today, and there are some faint clouds on the horizon. It's cold in the morning, so wear a thick coat. There is a breeze and you can see the national flag flying. 4. mapping. Heavy rain-wear rain boots, take an umbrella, can't hang clothes, the river is fast, cold and humid. 2 weather calendar 1. Multiple choice questions ( 1) C(2) B(3) B 2。 (omitted) 3. (omitted) 3 Temperature and air temperature 1. (1) √ (2) ×(3) √ (4) √ (5) × 2. Observation records (omitted according to measured records) 3. Observation records (omitted according to the measured records). 4. analysis. The temperature on this day gradually increased first, and then gradually decreased after the afternoon; During the day, the temperature is relatively low in the evening; The temperature at noon is as high as 30℃. 4 wind direction and speed 1. True or false. (1) √ (2) ×(3) √ (4) ×(5) √ 2. ( 1) B(2) A(3) A(4) C 3。 Observation records (omitted according to the measured records). 5 measured precipitation 1. True or false. (1) √ (2) ×(3) ×(4) √ (5) × 2. Multiple choice questions. ( 1) C(2) A(3) C(4) C(5) C 3。 Observation records (omitted according to the measured records). 6 cloud observation 1. True or false. (1) √ (2) ×(3) √ (4) √ (5) × 2. Multiple choice questions. ( 1) C(2) C(3) A 3。 Collect meteorological proverbs. Look at the clouds and know the weather. It is raining on the ground. There are castle clouds in the sky and thunderstorms on the ground. There was a broom cloud in the sky, and it rained for three days. It will be cloudy in the morning and rainy in the afternoon. Clouds are long in the east in the morning, but it won't last long if it rains. Clouds blocked the dam in the morning and it rained for three days. It is sunny in the morning and rainy in the evening. Flowers are blooming tonight, and tomorrow is the day of death. The sky is full of fish scales, so it doesn't rain when it's windy. There are pod clouds in the sky, and it will rain soon. The sky is overcast, and it will rain heavily soon. Lao Yun got off the bus, even if it was cloudy. Clouds eat fog and rain, and fog eats clouds. Clouds eat fire and rain, and fire eats clouds and sunny days. Dark clouds see the sun and it rains in the middle of the night. Dark clouds have white feet, and there must be heavy rain. The low clouds will persist, and it will rain soon. Clouds are long in the northwest and hail in the afternoon. Dark clouds are rising in the high temperature, and hail is about to fall. On the same day, dark clouds began to smoke and hail. Black Huang Yun turned over and hail was just around the corner. Black Huang Yun turned over and was about to lay ice eggs. The sky is full of waves, and there is rain that can't run away. Summarize our weather observation 1. True or false. (1) √ (2) ×(3) The third question needs to be judged according to the specific observation data (4) ×(5) √ 2. Sort out and analyze. ( 1) 9、 6、 2、 1、 0、 0; (2) 20 mm, 15 mm, 75 mm, 10 mm, (total) 120 mm unit exercise 1. (1) √ (2) √ (3) √ (4) × (5) √ (6) × (7) √ (8 )× (9) √ (10 )× 2. Multiple choice questions. ( 1) B(2) C(3) B(4) A(5) A 3。 (omitted) 4. choose Rainy day, fog, cold, stratus, west wind, strong wind. 5. (Blank indicates precipitation). Precipitation 1 month February April May July August September 1 October 1 month1February Our body unit1body structure1. Mapping. Head, neck, trunk, upper limbs and lower limbs. 2. True or false. (1) ×(2) √ (3) √ (4) √ 2 bones, joints and muscles 1. True or false. (1) ×(2) √ (3) ×(4) √ 2. Contact. Skull tower, excavator, desk lamp; Muscle excavator; Combined excavator, antenna, flap 3. Multiple choice questions (1) C (2) What happens when C3 moves (1) 1. Fill in the blanks. (1) oxygen, carbon dioxide and nitrogen; (2) gas exchange, oxygen and carbon dioxide; (3) (omitted) 2. True or false. (1) ×(2) √ (3) √ 3. Mapping. Nasal cavity, trachea, bronchus and lung 4. Explain. During the exercise, you need to consume a lot of oxygen, so the number of breaths will increase. What happens when you exercise (2) 1. Fill in the blanks. (1) lung, blood, heart, carbon dioxide; (2) (omitted); (3) Leave and return to 2. True or false. (1) √ (2) ×(3) ×(4) √ (5) √ 3. Contact. Earwash ball-heart; Pinching your hand will relax your heart muscle; Plastic tube-blood vessel 4. Explain. In the process of human movement, we need a lot of oxygen and nutrients, and produce a lot of carbon dioxide, which requires more blood to transport, so the heart will beat faster to transport more blood. Travel of food in the body 20 40 60 801001201401601. True or false. (1) √ (2) √ (3) ×(4) × 2. Contact. Break food and digest a small amount of starch; Stomach-temporary storage of food, preliminary digestion of protein; Esophagus-transporting food to the stomach; Large intestine-absorbs water from food scraps; Small intestine-the most important place to digest food and absorb nutrition. 3.( 1) Oral cavity, esophagus, stomach, small intestine and large intestine (2) Changes of food in the oral cavity of esophagus, stomach, small intestine and large intestine 1. Gnashing food; Amazing; Produce saliva and digest starch in food. 2. Front teeth, 8; Dog teeth, 4; Molar teeth, 16-20 (subject to reality). 3. True or false. (1) √ (2) √ (3) √ (4) × 4. The correct behavior to protect your mouth: don't eat very hot food, brush your teeth in the right way and rinse your mouth after meals. 7 cooperative human organs 1. True or false. (1) √ (2) √ (3) √ (4) √ (5) √ (6) √ (7) √ (8) √ (9) × 2. Mapping. Get up early and go to bed early, take part in appropriate sports activities, don't eat snacks before going to bed, wash your hands before and after meals, brush your teeth in the morning and evening, and don't be picky about food or partial eclipse. Unit exercise 1. Fill in the blanks. (1) See, touch, smell, taste (or observe, experiment, compare, experience, etc. ); (2) trachea, bronchus and lung; (3) exchange oxygen and carbon dioxide; (4) Esophagus, stomach, small intestine and large intestine. 2. (1) √ (2) √ (3) √ (4) × (5) √ (6) √ (7 )× (8 )× 3. True or false. ( 1) A(2) C(3) AB(4) C(5) C 4。 Short answer questions. (1) During exercise, the body needs more oxygen, so breathing is accelerated, the heartbeat is accelerated, and blood is transported to all parts of the body. (2) Exercise can promote all aspects of physical development, improve cardiovascular function, improve people's sensitivity and speed, and promote health. (3) For example, when exercising, the coordination of bones, muscles and joints is needed. The energy needed for exercise comes from food and needs to be digested and absorbed by the digestive system. More oxygen is needed during exercise, and the respiratory system must work faster. Therefore, the movement of human body embodies the coordination and cooperation of various organs. Comprehensive exercise 1. Multiple choice questions ( 1)C(2)B(3)A(4)C(5)B(6)C(7)A(8)B(9)A( 10)C 2。 True or false. (1) √ (2) √ (3) √ (4) × (5) × (6) √ (7) √ (8 )× (9 )× 3.4. Height 5. Answer: (1) Water-soluble substances: salt and washing powder. Insoluble in water: sand, flour and edible oil (2) heat, crush and stir. (3) air ear 6 of air stethoscope, (1) omitted; (2) The temperature rises gradually during the day, and then drops slowly. The highest temperature appears around 2 pm. Northwest, northeast, east, west, south, southwest and southeast.