Useful counseling materials for junior high school students

Useful counseling materials for junior high school students

Junior high school is a critical moment, and many students are anxious and don't know how to review. The following is the useful counseling materials I compiled for Xiaoshengchu. Welcome to reading.

I. Scientific knowledge

(1) Tools and machinery

1. machinery refers to various devices composed of mechanical principles. Levers, pulleys, ramps, axles, etc. They are all machines. Simple machines are also customarily called tools.

2. The lever has three points: force point, fulcrum point and resistance point. When the distance from the force point to the fulcrum is greater than the distance from the resistance point to the fulcrum, the lever saves effort; When the distance from the force point to the fulcrum is equal to the distance from the resistance point to the fulcrum, the lever is neither labor-saving nor laborious; When the distance from the force point to the fulcrum is less than the distance from the resistance point to the fulcrum, the lever is laborious. Whether the lever saves effort depends on the position of its three points.

(Can distinguish the three points of the lever and judge whether it is labor-saving)

3. The axle consists of a wheel and a shaft, which can save labor by applying force to the wheel. The bigger the wheel, the more labor-saving. The axle is a special lever.

4. The crown block is fixed in one place and cannot move with the movement of heavy objects, such as the pulley at the top of the flagpole; The moving pulley is not fixed, but can move with the movement of heavy objects. The crown block is effortless, effortless, but it can change the direction of force and can be regarded as an equal arm lever; Moving the pulley can not change the direction of force, but it can save labor, f =1/2 g. The pulley block can not only change the direction of force, but also save twice as much labor. The more pulley blocks (1 crown block and 1 moving pulley combined into 1 group), the more labor is saved, which is related to the number of rope strands wound on the moving pulley. That is f =1/n g.

A simple machine, such as the wooden board on the car carriage, is called inclined plane, which can save labor, the smaller the slope, the more labor, and the greater the slope, the more labor.

6. Bicycles use simple mechanical principles, such as levers, shafts and ramps. Among them, the lever includes a brake and a bell, the axle includes a handlebar and a pedal, and the ramp includes screws. (Master the relationship between the big and small gears of bicycles)

(2) shape and structure

1. Increasing the width and thickness of the beam and changing the shape of the material can change the bending capacity of the material. By changing the shape of materials, the bending properties of various steels and corrugated paper can be improved.

2. The arch can transmit pressure downward and outward, so it can bear a lot of pressure. When the arch is compressed, it will produce an outward force. Against this force, the arch can bear a lot of weight.

3. Dome, sphere and arch have similar characteristics. Dome can be regarded as a combination of arches, which bears the characteristics of high pressure and does not produce external thrust. A sphere can be regarded as an arch in all directions, which makes it stronger than any other shape.

4. The triangular frame has stability; Objects with small top and big bottom and light top and heavy bottom have good stability.

5. Cable-stayed bridge is composed of steel cable, pylon and deck. The cable is the main load-bearing component of the bridge, and the pylon is the main component supporting the cable. Cable bridges include cable-stayed bridges and suspension bridges.

(3) Energy

1. Current can produce magnetism. Electromagnet is composed of coil and iron core, which has the basic properties of producing magnetism when power is on and disappearing when power is off.

2. Changing the connection between the anode and cathode of the battery or changing the winding direction of the coil can change the north and south poles of the electromagnet.

3. The change of electromagnet's magnetic force is awesome, and its magnetic force is related to many factors such as coil turns and current intensity. Many coils, strong current and strong magnetic force.

4. The difference between electromagnet and magnet: (1) An electromagnet is magnetic only when it is electrified. (2) The north pole and south pole of electromagnet can be changed.

The function of toy motor is to change electricity into power. The basic working principle of a motor is the same: electricity generates magnetism and uses the interaction of magnetism to rotate. Small motor consists of shell, rotor and back cover. A magnet is arranged in the shell, the rotor comprises an iron core, a coil and a commutator, and a brush is arranged in the back cover. The function of commutator is to connect current and change the direction of current. When the small motor rotates, the brush contacts the three metal rings of the commutator in turn, and the direction of current passing through the rotor coil will automatically change.

6. Energy has many forms, such as electricity, heat, sound and light, and is also stored in food and fuel, which is called chemical energy. Moving objects also have energy, called kinetic energy (mechanical energy). Any object needs energy to work, and the energy in nature can be transformed into each other.

7. Electricity is a secondary energy source converted from other energy sources, and batteries convert chemical energy or light energy into electrical energy. The rechargeable battery converts electric energy into chemical energy when charging; When discharging, chemical energy is converted into electrical energy.

8. The energy possessed by coal, oil and natural gas ultimately comes from the sun. New energy mainly includes geothermal energy, wind energy, seawater kinetic energy, atomic energy (nuclear energy), biogas and solar energy.

biodiversity

1. Plants can be divided into flowering plants and non-flowering plants, including ferns, mosses and algae.

2. Animals are divided into vertebrates and invertebrates.

(5) The tiny world

1. Magnifier is characterized by a convex center and thin sides. Functions include: enlarging object image, imaging and focusing.

Rostain, an Englishman, first put forward the application of magnifying glass, and his student Bacon invented glasses to improve his eyesight. Presbyopic glasses are convex lenses, and myopia glasses are concave lenses.

3. Particles of salt, sugar, alkaline noodles and monosodium glutamate all have solids with regular geometric shapes. We call this solid substance a crystal. Many rocks are composed of mineral crystals. For example, granite is composed of feldspar, mica, quartz and other minerals.

4. The methods of making crystals are: reducing water and cooling.

Biologist Levin Hooke invented the world's earliest metal structure microscope with a magnification of 300 times, and discovered microorganisms. The correct operation method of microscope: setting-aiming-loading-focusing-observation. Evolution of human observation tools: naked eye-magnifying glass-optical microscope-electron microscope-scanning tunneling microscope.

6. All living things are composed of cells, which are the most basic structural units and the most basic functional units of living things. Biological life activities such as respiration, digestion, excretion, growth, development, reproduction and inheritance are all carried out through cells. 1663, British scientist Robert Hooke discovered cells with a self-made compound microscope.

7. Microorganisms include bacteria, viruses, fungi and some small protozoa. The microorganisms in the water mainly include paramecium, bell worm, trumpet worm, eye worm, amoeba, Chlamydomonas, Volvariella volvacea and so on.

(vi) Significant changes

1. We call what actually exists that can be observed directly or indirectly matter. The whole world is made of matter, and matter is constantly changing. Some changes do not produce new substances, which are called physical changes; Some changes produce new substances, which are called chemical changes. Chemical changes are always accompanied by physical changes.

2. The gas of carbon dioxide cannot support combustion and is relatively heavy; Dropping iodine into starch-containing substances will produce a new blue substance. Rust is the interaction between air and water. The way to prevent iron from rusting is to isolate iron from water and air. The main measure is to spray paint, put it in a dry place and make alloy.

3. Table of material changes

1. The moon is the closest celestial body to the earth and a satellite of the earth. The direction of its rotation and revolution is from west to east. The moon is about 1/4 in diameter, 1/80 in mass, 1/49 in volume and 1/6 in gravity. 1On July 20th, 969, the American "Apollo 1 1" spacecraft landed on the surface of the moon, and Armstrong left the first human footprint.

2. The various shapes of the moon during the waning and waning are called the phase change of the moon. The moon phases have different shapes in different periods of a month. The change of the moon phase is formed in the process of the moon's revolution around the earth, and the law of change is: from loss to circle and then to loss. Order: New Moon (the first day)-Emei Month (the fourth day)-First quarter moon (the eighth day)-Convex Moon (the twelfth day)-Full Moon (the fifteenth day)-Convex Moon (the nineteenth day)-Last quarter moon (the twenty-third day)-Emei Month (the twenty-seventh day).

There are many craters on the surface of the moon, which are characterized by chaotic distribution, large number, different sizes and different depths. The formation of craters is mainly related to meteorite impact and volcanic eruption.

Solar eclipse and lunar eclipse are astronomical phenomena formed by the movement of the sun, the earth and the moon. The moon runs between the sun and the earth. When the earth is in the shadow of the moon, an eclipse is formed because the moon blocks the light of the sun. There are three kinds of eclipses: total solar eclipse, annular solar eclipse and partial solar eclipse. The solar eclipse occurs on the first day of the lunar calendar; An eclipse is when the moon moves into the shadow of the earth, and the earth blocks the light from the sun to the moon. There are two kinds of solar eclipses: total solar eclipse and partial solar eclipse. The solar eclipse occurs on the fifteenth day of the lunar calendar.

5. The solar system is a celestial system centered on the sun, including eight planets (including satellites), dwarf planets and small celestial bodies (asteroids, meteors, comets, etc.). ) Around it. The solar system is a huge celestial system. The distances between the eight planets and the sun from near to far are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Among them, the closest planet to the earth is Venus, and Jupiter is the largest planet in the solar system.

6. Constellations are visual images of unrelated stars in the sky. If you look at it from different angles, the graphics are different. The most obvious symbol of Ursa major is the familiar Big Dipper, which consists of seven bright stars. Polaris can help you find your direction at night, and you can easily find it by using the Big Dipper in Ursa Major: the connecting line of two stars extends in front of the dipper, and there is a brighter star about five times the distance between the two stars, that is, Polaris. Polaris belongs to Ursa minor.

7. With the change of seasons, different representative constellations will appear in the sky. Constellations move in the sky. The figure composed of bright stars is the main symbol of the constellation.

8. There are many bright stars in the summer sky, among which three bright stars Tianjin IV (belonging to Cygnus), Vega (belonging to Lyra) and Altair (belonging to Eagle) form a huge triangle, which is called "Summer Triangle". The handle of the Big Dipper faces east in spring, south in summer, west in autumn and north in winter. Will know several common constellations.

9. The solar system and many stars together form a cluster called the Milky Way. The Milky Way consists of about 654.38+000 billion-200 billion stars with a diameter of 654.38+000 billion light years. Light travels at a speed of 300,000 kilometers per second. A light year is the distance that light travels in a year. It is a unit used to measure the distance between stars. The Milky Way is not the whole universe, and there are 654.38+000 billion galaxies similar to the Milky Way, collectively referred to as extragalactic galaxies. The universe is moving and expanding, and so are the celestial bodies that make up the universe. In descending order: Earth-Moon System-Solar System-Galaxies-Extragalactic Galaxies-Universe.

Can draw the life of the star evolution. )

10. China is recognized as the birthplace of rockets in the world. As early as 1700 years ago, the name "rocket" appeared in the ancient books of the Three Kingdoms period. China's space technology occupies an important position in the world: Shenzhou 5, Shenzhou VI and Shenzhou VII manned spacecraft have realized the flying dream of China people; Now the Chang 'e-1 lunar exploration satellite has been successfully launched.

(viii) Environment and us

1. A person's life will produce a lot of complicated (garbage). Discarded garbage (harmful to the environment).

At present, there are landfill and incineration methods to deal with garbage, but they will still have an impact on the environment. The hazards of landfill to the surrounding environment are: (1) giving off stench, polluting the air (2) breeding mosquitoes and flies, causing diseases (3) causing soil pollution, affecting agricultural production (4) polluting water bodies, etc.

2. Advantages of burning garbage: (1) It occupies a small area and reduces garbage; (2) Avoid groundwater pollution; (3) The generated heat can be used to generate electricity; Disadvantages: (1) consumes a lot of electric energy (2) leaves residue (3) and causes secondary pollution. A (well-designed) (landfill) can effectively reduce environmental pollution. It is very important to (reduce garbage), and the common methods are (reduce throwing away) and (reuse).

3. The following garbage can be reduced in daily life: (1) Double-sided printing can save paper; (2) Go out with your own drinking cup and buy less bottled drinks; (3) Use as little or no disposable goods as possible to reduce the waste of paper and plastic (over-packaging) and produce a lot of garbage. Some raw materials in garbage can be reused, including paper, metal, plastic and glass. This can (reduce garbage and save resources).

In order to recycle garbage effectively, we must change the habit of garbage mixing and classify and repackage domestic garbage. Garbage sorting and repackaging facilitate garbage (recycling) and partial (toxic garbage) treatment. Among the five substances that pose the greatest threat to the natural environment, batteries contain three kinds: (mercury), (lead) and (cadmium). Composting can effectively reduce garbage and form (fertilizer). The scientific methods to reduce solid waste are (reducing discarding), (reusing) and (recycling).

People need to use a lot of water in their lives, and water resources are in short supply. Due to (rapid population growth), (environmental pollution) and (global warming), at present, 60% of the mainland faces a shortage of fresh water resources, and more than 65,438,000 countries are seriously short of water, of which more than 40 are the most serious. In the case of shortage of fresh water resources, water pollution poses a threat to human beings and other organisms. Water pollution is mainly caused by (human activities).

6. Water pollution sources may come from (agricultural pesticides, fertilizers), industrial wastewater, oil pollution, household detergents, human excreta and animal carcasses. Sewage needs complicated treatment before it can be used. In addition to (precipitation) and (filtration), fresh water has to be treated with drugs (sterilization) in the waterworks, so as to meet the standards we use.

7. Sewage can only be used after (complicated treatment), and it is generally purified by three methods (physical method, biological method and chemical method). The physical method is mainly to separate impurities and larger particles in water, including plastic bags, vegetables and weeds. The biological method is to decompose the dirt in water through bacteria; Disinfection mainly adopts chemical methods, and the usual practice is to add chlorine gas, a human chemical agent, to effectively kill pathogenic microorganisms in water.

8. At present, the outstanding environmental problems are (garbage), (water pollution), (air pollution), (white pollution) and (accelerated extinction of species), and human beings are focusing on corresponding environmental protection actions. Reducing the emission of waste gas and waste is the most fundamental way to control air pollution. In recent years, China has actively promoted "Car Free Day" to save energy and protect the environment. The ways to reduce white pollution (plastic waste) are: (1) using paper bags and cloth bags (2) carrying food baskets to the market (3) reducing plastic packaging (4) using degradable plastic bags.

9. Due to (massive destruction of global forests) and (deterioration of marine environment), the extinction rate of existing biological species is higher than that of natural extinction (1000 times). Humans (indiscriminate hunting) and (excessive exploitation and utilization) make many biological resources on the verge of exhaustion.

10. Establishing nature reserves is an effective way to protect biodiversity. China's (Jiuzhaigou), (Changbai Mountain) and (Wolong, Sichuan) have all established nature reserves. Many environmental problems are caused by human activities, but human activities can also improve the environment.

Second, scientific inquiry.

1. The following table is the data obtained by students when lifting weights on inclined planes with different slopes. Please answer the questions according to the data:

(1) The conditions changed in this experiment are: the slope of the inclined plane.

(2) The constant condition of this experiment is: the height of the inclined plane.

(3) As can be seen from the above data, the largest slope is _ _ c _ _, and the smallest slope is _ _ b _ _. (4) This experiment tells us that the smaller the inclination of the inclined plane, the more labor-saving.

2. Leverage research

Problems to be studied: Understand the working principle of lever.

Material: lever ruler, hook code.

Process and method:

1. After adjusting the lever ruler to a balanced state, first hang two hook codes on the second hole on the left side of the lever ruler, and try to hang two hook codes on the first, second, second and fourth holes on the right side of the lever ruler. What state will the lever ruler be in?

2. Change the position and number of hook codes on the left and right sides of the lever ruler respectively, and observe what will happen to the state of the lever ruler? What laws can be found from it?

Experimental results:

1. When the distance between the force point and the fulcrum is as far as the distance between the key point and the fulcrum, and the force is the same, the lever ruler is balanced.

2. The force point is far from the fulcrum, and the key point is close to the fulcrum. This lever can save labor.

3, the stress point is close to the fulcrum, and the key point is far away from the fulcrum. This lever doesn't save effort.

Thinking: What other materials can be used to study the balance principle of lever? For example, can you do this experiment with a ruler, eraser, pencil and other materials? )

3. Experimental Name: Research on Axis

Research question: When will the axle save effort?

Experimental materials: screwdriver, thread and hook code.

Experimental process: thread the screwdriver handle, hang a hook code on the other end, hold the handle with your hand, and rotate the screwdriver to lift the hook code upward. On the contrary, tie the thread to the handle, hold the handle in hand, and turn the screwdriver to make the hook code upward.

Mention; What does it mean to compare the feelings of two experiments?

Thinking: In the experiment, which part of the screwdriver is the wheel and which part is the shaft.

4. Name of experiment: the function of inclined plane

Design purpose: Through scientific experiments, collect evidence and realize the labor-saving principle of inclined plane. Materials: wooden boards (of different lengths), wooden blocks, weights and dynamometer.

Process and method: 1. Support one end of a wooden board on the desktop and the other end on the wooden block to make it an inclined plane. Put different weights at the lower end of the inclined plane and pull it up along the inclined plane with a dynamometer. Observe how much force is used. 2. Support it with that wooden block, build an inclined plane with wooden boards of other lengths, choose a heavy object to pull up one by one along these inclined planes of different lengths, and observe how much force is used respectively.

Experimental result: 1. It is found that the force used to pull an object down from an inclined plane, whether it has wheels or not, whether it is large or small, and whether the surface is rough or smooth, is less than the force used to lift it vertically.

2. It is found that the longer the board is, the smaller the slope is, the more labor-saving it is, and the greater the slope is, the less labor-saving it is. Lifting heavy objects directly vertically is equivalent to a 90-degree slope, which is not labor-saving at all.

Note: Pay attention to whether it is labor-saving to pull the weight up along the inclined plane, and only compare it with the force used when lifting the weight vertically can we know.

5. Research topic: The relationship between paper bending strength and paper thickness.

Experimental materials: two paper cups and several paper clips.

1. Experimental speculation: The thicker the paper, the stronger the bending resistance, and the thinner the paper, the weaker the bending resistance.

2. Conditions to be changed: paper thickness.

3. Keep the same conditions: the size and width of the paper, the weight and position of the needle.

4. Experimental method: ① Build a paper bridge with a width of 10 cm with two paper cups and a piece of white paper, then put paper clips on it and record the number of paper clips that the paper bridge bears. Repeat three times. (2) Under other conditions unchanged, replace one piece of paper in the first step with two pieces of paper, and record the number of paper clips supported by the paper bridge of the two pieces of paper. Repeat three times. (3) Under other conditions unchanged, replace one piece of paper in the first step with three pieces of paper, and record the number of paper clips supported by the paper bridge of the three pieces of paper. Repeat three times. ④ Analyze the data and draw a conclusion.

5. Description and conclusion: The thicker the paper, the stronger the bending resistance, and the thinner the paper, the weaker the bending resistance.

6. Answer the questions according to the experimental data provided in the table below.

(1) This group of students studied the relationship between the thickness of materials and their flexural capacity.

(2) The conditions changed in this experiment are: the thickness of the material.

(3) The invariable conditions in this experiment are: material specification, material width, material length and gasket weight.

(4) By analyzing the data in the table, it can be concluded that the thicker the material, the greater the bending capacity. .

7. Experimental name: Magnetic force of electromagnet

Question to be studied: What is the relationship between the magnetic force of electromagnet and it?

Material: battery, enameled wire, nail, pin or paper clip.

Process and method:

1. Wrap a certain number of enameled wires on the nail, then connect different batteries in series, and observe the number of stitches sucked up.

2. Wrap the enameled wire with different turns on the same nail, then connect the batteries with the same turns in series, and observe the number of pins sucked up respectively.

Experimental results: 1 electromagnet connected in series with a large number of batteries attracts more pins, indicating that it is more magnetic.

2. The more windings an electromagnet attracts, the more stitches it attracts, indicating that its magnetic force is greater. Note: the research proves that the magnetic field strength of electromagnet is determined by four factors: first, the material of iron core (the magnetic field of cooked iron core is the strongest, while the magnetic field of hollow core is the weakest); The second is the number of coils wound on the iron core; The third is the current intensity in the coil; The fourth is the distance between the winding and the core.

Thinking: Through experiments, what factors are related to the magnetic force of electromagnet?

8. Research topic: Relationship between magnetic force of electromagnet and current intensity.

Experimental material: battery box nail enameled wire paper clip

1. Experimental speculation: The greater the current intensity, the greater the electromagnet magnetic force, and the smaller the current intensity, the smaller the electromagnet magnetic force.

2. Conditions to be changed: current intensity

3. Conditions that remain unchanged: coil turns, coil size, iron core size and paper clip weight.

4. Experimental method: ① Make a battery iron of 100 coil with nails and enameled wire, connect the battery, suck paper clips with electromagnet, record the number of paper clips, and repeat for three times. (2) replace one battery with two batteries, other conditions being unchanged, and record the number of times the electromagnet attracts the paper clip at this time, and repeat it three times. ③ Replace two batteries with three batteries, other conditions being unchanged, and record the number of times that the electromagnet attracts the paper clip at this time, and repeat it for three times. ④ Analyze the data and draw a conclusion.

5. Explanation and conclusion: The greater the current intensity, the greater the electromagnet magnetic force, and the smaller the current intensity, the smaller the electromagnet magnetic force.

9. When studying the relationship between the magnetic force of electromagnet and the current intensity in the coil, Xiao Ming got the following experimental figures through experiments.

According to.

① The conditions to be changed in the experiment are: current intensity (number of batteries). ② The invariable conditions in the experiment are: coil number, coil size, iron core size and paper clip weight.

③ By analyzing the data recorded in the table, it is concluded that the greater the current intensity, the greater the electromagnet magnetic force, and the smaller the current intensity, the smaller the electromagnet magnetic force.

10. The students in Group 2, Class 6, Sunshine Primary School are studying the factors of rust. They used three plates of the same size, two of which were filled with water and vegetable oil and three nails of the same size. One nail is exposed to air in an empty plate, the other nail is completely immersed in vegetable oil, and the other nail is half in water. Observe and record every day. (The observed phenomena are as follows)

(1) The above experimental methods are: comparative method.

(2) Iron rusts fastest in water dishes and slowest in vegetable oil dishes.

(3) What conclusions are drawn from the above experiments:

The conditions for rust generation are oxygen and water.

1 1. experimental name: "crater mountain" gene simulation experiment.

Question to be studied: How may the "crater" be formed?

Materials: sand (several in each group), syringes, hoses (one in each group), heavy balls (one in each group), and instruments prepared by students themselves.

Process and method:

1. Connect the syringe to the hose and insert the hose into the bottom of the sand.

2. Push the water out of the syringe forcibly and observe the phenomenon.

3. Hit the sand with a heavy ball, observe the phenomenon and record it.

Phenomenon: the water in the syringe will come out of the sand pile and form a volcano; When a heavy ball hits the sand pile, there will be a crater-like pit in the sand pile.

Thinking: What does the phenomenon produced by the experiment show? What does the heavy ball and the water sprayed by the syringe simulate in the experiment?

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