2 thoughts on “Children's middle class self -made teaching aids. Please answer speed! Urgent ...!!”

  1. Lindsey

    Which candle is destroyed first?
    we have done the experiment of pouring carbon dioxide in the past with two highs and one high. But what will happen if the cup is buckled on the two burning candles (as shown in the figure below)?

    2005-12-08
    The mystery of "Dog Demon"
    Questions: There is a "dead dog hole" near Naples, Italy, and animals such as dogs, cats, Go in, struggling for a few minutes, and people can pass this hole safely. The superstition said that there is a "Dog Demon" in the cave. Why is there such a strange phenomenon?
    one day, the scientist Boner made a special trip to this hole. He looked around in the cave. He never saw the "Dog Demon", but saw a lot of clocks hanging in the cave. There were bubbles in it. All this made Boner suddenly realize. Then he did two simple experiments in the cave and discovered the secret of the "Dog Demon". Do you want to know?
    Experiment: In a 250 ml burn, put one high, one low, two burning candles (as shown in the figure), collect a bottle of carbon dioxide with a 10 mL gas cylinder, pour it into the cup What phenomenon happened?

    Mill do you guess which two experiments did Porman do in the cave and discovered the secret of "Dog Demon"?
    2005-11-21
    The carbon dioxide fun experiments
    It Tianjin Tanggu District Education Center Kang Yongjun
    This may be a painful thing for many students, but in chemistry There are many interesting experiments that have the aftertaste of interest, and let us learn knowledge in happiness. Let's learn through some fun experiments of carbon dioxide together!

    . Bottle Swallowing Egg

    Themming design a interesting chemical experiment: put a slightly larger egg in the mouth of Guangkou bottle in the bottle, first immerse the eggs in 10%of the acetic acid In the middle, after the egg shell becomes soft, take out the eggs, add a sufficient amount of CA (OH) 2 solution to the wide mouth bottle, and then pour in a sufficient amount of CO2 to quickly block the bottle mouth of the eggs, oscillate the wide mouth, oscillating extensive mouth The bottle, the egg was quickly swallowed by the bottle. Please analyze the reasons: ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________ of.

    [Analysis] This question is to closely combine the pressure in the physics discipline with the principles of chemistry. The main component of the eggshell is CACO3, which can react with the acetic acid (the main ingredient of home vinegar) to generate the material that is soluble in water and soften the egg shell. The CO2 in the bottle reacts with the NAOH solution, which makes the pressure in the bottle lower than the external atmospheric pressure, and the eggs are "swallowed" into the bottle.

    . The egg that dances

    In a large amount of tube dilute hydrochloric acid to a large amount of cylinder, and then put a fresh egg in the measuring cylinder (as shown in the right picture). At the bottom, after a while, the eggs slowly floated upwards, floating on the liquid surface, shaking the tube, and the eggs sank again. "Dance" up and down, but after all, it is "dance". do you know? Eggs can dance in hydrochloric acid, without the help of carbon dioxide. Please explain the truth.

    [Analysis] The egg shell contains calcium carbonate. Calcium carbonate and hydrochloride react to generate carbon dioxide. The generated carbon dioxide bubbles are attached to the surface of the eggshell, which increases the volume of the eggs and increases the buoyancy of the eggs. Eggs will sink, so that the eggs will float up and sink and circulate.

    3. The floating balloon

    The color ball balloon in the large cup, CO2 in the red balloon, air in the blue balloon, the air in the blue balloon, the air contains air in the blue balloon, Two balloons on the bottom of the cup. Slowly dump a bottle of CO2 gas into the large cup, and find that one of the balloons floats up. Press it gently with your hands, the hand is loose, and the balloon will float again, which is very interesting.

    Please analyze and answer: ______________ color balloon floats, the reason is that ______________.

    [Analysis] This question is applied to buoyancy knowledge in physics disciplines. Because the density of CO2 is larger than air, the blue balloon floats.

    . The teased candle

    The burning candle is fixed to the bottom of the cup, a certain amount of egg shell is added to it, and then an appropriate amount of diluted hydrochloric acid is injected along the inner wall of the cup (not drowned the candle hydrochloric acid), Observed the extinguisher of the candle flame, this experiment shows that the nature of carbon dioxide is:
    ① _________________________; r
    ② ____________________

    This use of these properties of carbon dioxide can be used to use carbon dioxide to ____________________________________.

    [Analysis] The egg shell contains calcium carbonate. Calcium carbonate and hydrochloride react to generate carbon dioxide. Carbon dioxide can also react with calcium hydroxide to generate calcium carbonate to reduce the gas pressure in the bottle, so slightly soft shell eggs than the bottle mouth will fall into the bottle. The density of carbon dioxide is larger than air. It can neither burn nor can it support burning. It can be used to extinguish fires.

    The students, do you master the nature of carbon dioxide through the fun experiments above, and summarize it yourself.
    The dyes in red ink
    Questions: Red ink water is often used by teachers to correct students' homework. Its color and white paper and blue and black ink form a large contrast, making the teacher's correction look particularly eye -catching. So, how many dyes are there in red ink?
    Experiment:
    Step 1: Take a chalk, point a little red ink on a thicker end of 1 cm (just dip it in a little red ink with a fine glass rod, do not use a dropper drop. Because doing this will make the red ink too much), the diameter of the red ink after ordering is about 1 mm.
    Step 2: Add alcohol to the exquisite fluid in the dine, keep the height of about 0.5 cm. Then stand down the chalk's big head and stand in alcohol, but the liquid surface of the alcohol should not be in contact with the red ink. Observe carefully.
    The phenomenon:.
    S compete for color
    Chen Shiquan
    In the preparation of a glass test tube, which is in the inside of nearly 1/3 of the water, dripped in a few drops of iodine, and shakes it tightly. The solution is light brown, commonly known as "iodine water".
    In the test tube is slightly tilted, and the tube wall is slowly dripped into colorless and transparent clean gasoline until the liquid surface rises to 2/3 height of the test tube. So you can see two layers of liquid appearing in the test tube: The lower layer is light brown iodine water, and the upper layer is colorless and transparent gasoline. You can tighten the bottle and shake the test tube constantly until the liquid inside is mixed, and then stand upright and static. After a while, strange! The liquid inside changes: the relatively heavy water sinking in the lower layer almost becomes no color, but the gasoline floating on the upper layer becomes purple. so, what happened?
    turns out that iodine is not easy to dissolve in water, but it is very easy to dissolve in gasoline. When you shake the test tube fiercely, the iodine water and gasoline inside have a chance to fully contact. As a result, most of the iodine in the water is "taken away" by gasoline, so the gasoline becomes purple -red, and the water that loses iodine at the same time is lost. It also lost color.
    In "Do Hands"
    The fun minor experiment
    . Flying of the air cushion
    Plip a glass with hot water and leave a little hot water in the cup. Then quickly buckle the cup on the smooth desktop. At this time, gently blowing it towards the cup or pushing it with feathers, and the glass ghosts made God easily slide on the desktop, just like ice skating, there was almost no friction. What is going on?
    This is because when the cup quickly reflects on the desktop, the hot water in the cup is poured out, and the air enters. The air occurs with thermal expansion, so that the cup buckled on the desktop slightly holds up. At this time, the cup no longer comes in contact with the desktop, but supports a thin layer of water film and "flying pads". Therefore, the friction between the cup and the desktop becomes very small. Therefore, as long as there is a small external force, the cup will slip forward!
    . The friction produces hot
    The right hand pinch the copper wire and pull it to the right, let the copper wire slide the left hand in the holding, at which time the left hand will feel hot.
    This pinching the copper wire with both hands, quickly bending back and forth multiple times, and the bending of the copper wire will become hot and hot. Is this what happened?
    This is because object friction can produce heat. In the above two experiments, the first experiment was the friction between the copper wire and the hand. The second experiment is the internal friction between the internal friction between the copper wire when the copper wire is bent. Both of these situations are converted from mechanical energy to thermal energy through friction.
    3. The peculiar frozen
    The experiment (1) Put the soda in the refrigerator to freeze to the degree of freeness (but not frozen). Take the soda out of the refrigerator and open the bottle cap. Although in the room temperature, the ice cubes are quickly out of the soda bottle.
    The experiment (2) Put a bottle of ordinary cold water, wrap it in a cloth and put it in the refrigerator for freezing. After a long period of time, the water in the bottle became ice, but the bottle was bloated.
    Why is this? It turns out that this is because in the experiment (1), the soda contains a large amount of carbon dioxide, so the freezing point is lower and it is difficult to freeze. After opening the bottle cap, after the carbon dioxide gasification, the freezing point rises; at the same time, the carbon dioxide gas should be absorbed during gasification to further reduce the temperature of the soda. As a result, the ice was quickly out of the bottle.
    In the experiment (2), the volume of water should be increased when frozen, so the bottle is swollen. It is used to prevent the glass fragments scattered into the refrigerator when the bottle is bloated.
    In "Second Class"
    The thermal conductive experimental
    Hou Zhuru, Hou Zhuru, Second Primary School, Jiaocheng County, Shanxi Province
    1. Experimental device diagram (Figure 1)

    . Experimental materials
    The copper wire, wire and aluminum wire of the same thickness; candles; match; Evil; Vaselin oil.
    . The production process
    1. Make a "L" bracket with a wooden board. See Figure 2 in size.
    2. Tied one end of the copper wires, wire and aluminum wire of the same thickness, and the other end is fixed on the wooden board and is 10-15 cm higher than the bottom.

    3. Take the same distance from the binding ruler from the end of the binding. The same distance is measured by the same distance, and the matching of the match with Evanguary oil is used to stick the match.
    4. Put the candle in a bundled position.
    . Experimental phenomenon
    After lit the candle, about 2 to 3 minutes of the matches on the copper wire fall first, the matches on the aluminum wire fell, and the matches on the wire finally fell.
    . Experimental results
    1. Simple production and obvious phenomenon.
    2. Copper wire is the best heating, aluminum wire is medium, and the wire is the worst. (Instructor: Lu Qiong)
    2007-12-13 People Teaching Network

    Self-made simple lung live volume meter
    Zhongshan Middle School Tian Weimao
    . Material
    (1) Production material
    1. Bringing a transparent plastic barrel with a lid (such as plastic barrels equipped with golden fish edible oil, 5 liters; or fresh orange multi -plastic plastic Bottle, 2 liters), 60 ~ 80 long latex tubes (more than twice the height of about plastic barrels), glass tube.

    2. Waste enamel tanks or paint boxes (inner diameter is 8 ~ 10cm, and height is 9 ~ 11cm).
    (2) Other use materials
    500 ml measuring cups, 250ml measuring cups, straight ruler, triangular ruler, oily mark, alcohol spray lamp, porcelain bowl fragment, scissors, knife, etc.
    . The principle of production
    The lung volume refers to the gas volume of the most shiring gas after a deep absorption. Because the density of the human body is lighter than the water, it will rise in the water, so the "drainage method" can be used to make a simple lung activity meter. Put the water in the water in the plastic bucket and put it in the water. Blow the ducts into the barrel through the catheter. Use the gas to increase the water at the bottom of the barrel with the principle of automatically flowing down and falling under the water. The volume of the human body blowing out the gas is the volume occupied by the water discharged in the barrel, that is, the volume of the empty part in the barrel.
    . Production method
    1. Signing scale
    (1) Wash the plastic barrel clean.
    (2) Plastic barrels are on a horizontal desktop. The amount of dosage cup is 500ml of water pour into the plastic barrel. After the water surface is calm, in the center of the two planes of the dental parallel, use the ruler to parallel with the plane of the water with the water. The horizontal and water surface overlap. (In the actual operation, adjust the distance between the tip of the tip of the nib and the plane of the water and the plane of the water, so that the scale line of the painting is overlapped with the water surface level to reduce the error.) The two horizontal lines of the two horizontal lines are drawn vertical line vertical lines. Next, the horizontal scale should be drawn on the left side of the two vertical lines. The specific method is: 100ml of water, pour into the plastic barrel, and wait for the water surface to calm down. After the water surface is calm, the water surface is calm. Draw a 1cm long horizontal line to coincide with the level of the water surface; pour 100ml of water, repeat the above operations, just use 1.5cm long horizontal line at 1000ml, 1500ml, 2000ml, 2500ml, ... at the scale, the rest is 1cm long horizontal horizontal horizontal horizontal horizontal horizontal Wire. It is advisable to draw until the 5000ml scale line. (In actual operation, because the surface of the selected plastic barrel is uneven, the width between the scaled lines drawn is not uniform, and the transparent plastic barrel that can be found on the surface is best. Reading with him.)
    (3) According to the characteristics of students' age, body, and hands -on operations according to the equipment in the third grade of the equipment, we also used a large bottle of fresh orange with a volume of 2L. Well, the scale is accurate to 50 ml. It is especially suitable for students who have just entered the third grade.
    2. Make a catheter
    (1) Burn a 90 ° straight -angle -curved glass tube with alcohol spray lights. Essence Make another straight glass tube of about 8cm in length, and it also melted smoothly at both ends of the section of the two ends to blow the mouth of the lung volume meter.
    (2) The straight glass tube and curved glass tube are connected to both ends of the latex tube to make a catheter.
    3. Production bracket
    (1) The actual use of the bracket
    It in the teaching we found that when the third -year elementary school students are just being measured, the plastic bucket filled with water is poured pouring water. In the pot, the plastic barrel is easy to slide, so it is advisable to make a heavier bracket supporting plastic barrel with a heavier with a larger area at the bottom. At the same time, the plastic barrel should be vertically stood up to accurately read the measurement value. However, in the actual measurement, the students need to make the plastic barrel vertically vertically. It is difficult to operate. In order to make students' measurement activities more scientific and accurate, it is certainly easier to operate with a bracket.
    (2) The production method of the bracket
    This on the bottom of the outer wall of the abandoned enamel cylinder or paint box to cut a hole with a high × × 9cm length of 7cm × 9cm. Cut a hole with a height of 5cm × 5cm. Use a knife to smooth the edge of the hole in the edge of the cave. In this way, even if the bracket is made.
    . How to use

    1. Put in a small half pot of water in a flat basin and put the bracket into the pot.
    2. Fill the plastic barrel with water, tighten the lid, put it into the basin and put it on the stent, soake the barrel mouth into the water, then unscrew the lid, insert the right -angle glass tube into the barrel mouth, and insert it into the barrel. And adjust the plastic barrel to keep it vertically.
    3. Hand holding the mouth, stand deep and inhale to the maximum, the lips are tightly blowing the mouth of the glass tube. Read the value corresponding to the scale along the horizontal position, this value is the measured lung capacity. (Testing the lung volume test in the physical examination, the tester needs to measure 2 to 3 times, each time the interval is more than 30 seconds, and the test is taken again.)
    4. As a glass tube used as a blowing mouth, After each student is used, the saliva should be cleaned from the straight glass tube, and then strictly disinfected with alcohol to be used by the next person.
    . The meaning of use in teaching
    The value of a precise lung activity meter (electronic and cylinder) ranges from hundreds of yuan to thousands of yuan, which is very expensive. Equipped. Although this self -made simple lung activity meter does not have the standards produced by regular manufacturers, it can make up for the lack of teaching instruments. It can not only be used in the teachings of science courses in the third grade, but also use it in physical education courses at all stages of student growth (physical measurement). In the teaching, guide students to make measurement records at different ages, count the lung capacity of the classmates in the class, and experience their growth and changes from it. They can also analyze the influence of the gender, age, their own health status and participation in physical exercise on the lung volume, which stimulates students Learn the interest of science, improve the scientific literacy of students, and promote the comprehensive development of students.