Analysis of Notes on "Density" Trial Lecture in Teacher Recruitment Interview

20 17 Analysis of Notes on "Density" in Teacher Recruitment Interview

The writing of teacher qualification examination papers, the examination work and the issuance of examination result certificates belong to the qualification examination for teachers in kindergartens, primary schools, junior middle schools, senior middle schools and secondary vocational schools and the qualification examination for internship guidance teachers in secondary vocational schools, which is organized and implemented by the education administrative department of the people's government at or above the county level. So, the following is the analysis of the audition handout of Density that I share with you. Welcome to learn from it.

First of all, talk about textbooks.

This excerpt is from the second quarter of Chapter 6 of Grade 8 of People's Education Press. Density is a physical quantity used to describe the mass of matter in unit volume. Density can also be extended to the ratio of a quantity to a range, such as the abbreviation in this case, such as population density.

Second, the teaching objectives

1. Knowledge and skills

(1) Understand the physical meaning of density.

(2) Using density knowledge to solve simple practical problems.

2. Process and method

(1) Find out the relationship between the mass and volume of the same substance through experimental exploration activities.

(2) Learn the scientific thinking method of defining the concept of density with the invariance of the mass-volume ratio of the same substance (the essential feature of the substance).

3. Emotions, attitudes and values

Density reflects the characteristics of matter itself. Through inquiry activities, students' understanding of material properties is expanded.

4. Teaching AIDS and learning tools

(1) Wood blocks, aluminum blocks and iron blocks with the same volume.

(2) A number of wood blocks, aluminum blocks and iron blocks with different qualities and sizes.

(3) 1 pallet balance and weight.

(4) 1 scale.

Third, the teaching process

1. Introduce new courses

Student activities: think and do.

Let the students weigh the mass of different substances, such as wood, aluminum and iron, with the same volume.

Students will realize from the weighing results that substances of the same size but different kinds have different qualities. Show the differences in properties of substances in this respect.

2. New curriculum teaching

(1) Explore: the relationship between the mass and volume of the same substance.

Through the top? Thinking about doing it? Question: What is the relationship between the mass and volume of the same substance?

Speculation: The larger the volume, the greater the mass of the same substance. If the volume doubles, will the mass double? That is to say, is the mass of the same substance directly proportional to its volume?

Take several aluminum blocks with different sizes, measure their mass with a balance, calculate their volume after measuring their side length with a ruler, list the tables, then draw points on the grid paper with volume V as the abscissa and mass M as the ordinate, and then connect these points.

From the measured data, the mass and volume of the same substance will increase; The conclusion that the mass will decrease and the volume will also decrease. By visualizing the measured data, it will be more intuitive to get that the mass of the same substance is linearly related to its volume, that is, the mass of the same substance is directly proportional to its volume.

Replace the aluminum block with iron block and repeat the above experiment.

The mass-volume ratio of each aluminum block and iron block is calculated separately, and it can be concluded that the ratio is a constant value. This invariance of proportion reflects the characteristics of matter itself. For different substances, the linear relationship between mass and volume is represented by different straight lines passing through the origin. In other words, the proportions of various substances are different.

(2) Explanation: The ratio of mass to volume is the mass per unit volume; The mass per unit volume of the same substance is the same, but the mass per unit volume of different substances is generally different. So the mass per unit volume reflects a characteristic of matter, which is physically expressed by density.

(3) Definition of density: The mass per unit volume of a substance is called the density of this substance.

(4) density formula

Density = mass/volume

Explain:? Density; M stands for quality; V stands for volume. ? = Male/Female

The teacher pointed out: Attention: (1)? How to write and read. (2) Density is only related to the kind of substance, and has nothing to do with the mass and volume of the object.

(5) Density unit

International unit of density: kg/m3 (kg/m3)

Other density units: grams per cubic centimeter (g/cm3).

1 g/cm3 = 1000 kg/m3

(6) Homework after class

Let the students look at the density values of some substances (solid, liquid, gas) in the textbook, and let the students look up the density values in the density table. Guide students to read the density values of various substances listed in the table, and form some specific understanding of the density of those common substances, such as gold is denser than copper, copper is denser than iron, ice is denser than water, and remember the density of water.

(7) Give an example

Teach students how to calculate density with physical formula. Students are required to calculate according to a certain format and steps, not only to write formulas and numbers, but also to write necessary text descriptions. In particular, we should emphasize the operation of the unit and remind students to write correctly and not to miss it.

Fourth, blackboard design.

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