The Breakthrough of the Difficulties in the Teaching of "The Movement of the Earth" in Senior Three Geography —— The Difficulties in Senior Three Geography

The teaching of "the movement of the earth" has always been a difficult point for teachers and students. The content of this section is relatively simple in the textbook, but it has become a stumbling block for many senior three students to learn geography because of its many related knowledge points and high spatial imagination requirements. Because the content of this section cannot be understood thoroughly, it is easy to cause students' self-confidence in learning geography to decline, or even give up geography. The author has been engaged in geography teaching in senior three for many years, and found that if we can integrate the teaching content of textbooks, simplify and organize the comprehensive knowledge, supplemented by carefully combined targeted training, first consolidate a single knowledge point, and then carry out comprehensive exercises and expand thinking, we can achieve good teaching results. The author divides the main difficulties of this section into four parts, first breaking through each part one by one, and then strengthening and consolidating, so that students can learn with confidence and gain something.

First, the longitude and latitude network

This part is the content of junior high school geography, but because of too long time, many students have lost their memory; This part is also the basis of students' future study, which directly affects their future geography study, so it is necessary to review some junior high school knowledge first. To increase the knowledge of geography in senior high school on the basis of longitude and latitude network in junior high school, I divide this part into seven parts to teach: (1) the characteristics of longitude and latitude lines; (2) division and calculation of latitude and longitude; (3) judgment of latitude and longitude; (4) the division and judgment of the eastern and western hemispheres; (5) calculating the longitude and latitude distance online; (6) judging the relative direction between two points; (7) Determination of the shortest distance on the sphere.

Second, the question of time.

The curriculum standard requires mastering the skills of geographical calculation, including the calculation of time zone and time zone, the calculation of local time and longitude, and the international international date line problem. Single time calculation is relatively simple, and students can be trained skillfully. The date dividing line is the difficulty in this part, which requires students to master two date dividing lines firmly. One is longitude 180, which passes through 180 from west to east, and the longitude date is reduced by one day, which becomes the basis for determining longitude 180; The second is the meridian at 0 o'clock in life, which can be obtained by calculation or analysis, such as the midpoint of the hemisphere at night. The interpretation of these two meridians is a difficult point.

For example, the picture on the right shows the location of the terminal line in a solar term. In the figure, the termination line is tangent to the polar circle. At this time, it is Saturday in London and Sunday in Beijing. Look at the picture and answer the following questions: draw the direction of the earth's rotation in the picture and shade the area that has entered Sunday.

Analysis: the stem of the question does not give the northern and southern hemispheres, so the determination of the northern and southern hemispheres is a difficult point. If it is the northern hemisphere, assuming OC is the zero-time meridian, then London and Beijing are located on the same day, assuming OD is the zero-time meridian, and London and Beijing are still located on the same day, then it should be in the southern hemisphere; Since it is Saturday in London and Sunday in Beijing, it can be judged that OD is zero meridian. As shown in the figure.

Third, the terminator line, judge the terminator line.

Four fixed-point judgments of 0, 6, 12 and 18; The length of day and night, calculate sunrise and sunset; The relationship between the terminal line and latitude and longitude, and the relationship between the length of a day and the direct point of the sun are all described and consolidated in this part.

(a) interpretation of the termination line.

The key to interpretation is to judge the direction of rotation. The earth is from west to east.

Turn, in the top view centered on the pole, the northern hemisphere rotates counterclockwise and the southern hemisphere rotates clockwise; On the side view, it appears from west to east and from left to right. If the direction is determined, then along the rotation direction, the morning line is toward the light and the dark line is toward the darkness.

(2) four-point fixed-point judgment

The midpoint of the solar hemisphere is 12, the midpoint of the night hemisphere is 0, the termination line is tangent to latitude, and the tangent point is midnight12; 0 am; On the equator, the meridian passing through the intersection of the equator and the morning line is 6 points, and the meridian passing through the intersection of the equator and the faint line is 18 points. This content should be practiced on various lighting maps.

(3) Calculation of the length of day and night and the time of sunrise and sunset

There are many formulas about this part, and the key is to understand the calculation method and achieve fast operation. If the midpoint of the night hemisphere is 0 o'clock and the midpoint of the sun hemisphere is 12, it is easy to calculate the length of day and night and the time of sunrise and sunset. As shown in the example on the right.

(d) The relationship between the termination line and latitude and longitude.

The included angle between the terminal line and the meridian is 23 26' on the second day, and 0 on the second day, which means coincidence. The included angle is equal to the latitude of the direct point of the sun, and the terminal line is tangent to the latitude, and the tangential latitude is the latitude where the diurnal extreme value appears.

(5) The length of a day varies with the point of direct sunlight.

To put it simply, which hemisphere is the direct point of the sun? Which hemisphere has long days and short nights? The higher the latitude, the longer the days and the shorter the nights. Which hemisphere does the direct point of the sun move to? The days in this hemisphere are getting longer and the nights are getting shorter.

Fourth, the height of the sun.

The height of the sun is the abbreviation of the sun's altitude angle, which is the included angle between the sun's rays and the ground plane. This part includes the calculation of the noon sun height, the judgment of the coordinates of the direct point of the sun, the midnight sun height, the solar water heater, the distance between buildings and four conclusions drawn from the calculation of the noon sun height. The problem of noon (midnight) sun height can be calculated by "latitude difference = (noon, midnight) sun height difference"; The angle between the solar water heater and the ground and the distance between buildings can be explained to students. Four conclusions are difficult for students to learn, and they should be illustrated by examples: (1) equation: the latitude of the direct point of the sun is equal to the height of the sun at the extreme day; (2) Complementarity: the latitude of the direct point of the sun and the latitude of the extreme day (night) are complementary; (3) Double: the extreme latitude line during the day, and its noon sun height is twice the latitude of the direct point of the sun; (4) The relationship of 1/2: the latitude of the direct solar point is the sum of the noon sun height and the midnight sun height on a latitude of the polar day1/2. A simple example can be as follows: the direct sunlight is 20 N, then the noon sun height in the North Pole is 20 (equal); The extreme day (mutual redundancy) appears at 70° N；; The height of the sun at 70 N at noon is 40 (2 times); 80 N The noon sun height is 30, and the midnight sun height is 10 (1/2).

In a word, these four parts complement each other and are often combined together. First, step by step, a breakthrough. After students master every knowledge point, they will not be unfamiliar with high comprehensive topics. Over time, students will gain something from geography, and the more they learn, the simpler they feel, thus cultivating their self-confidence in learning geography.

(Author: No.1 Senior High School in Lingbao City, Henan Province)

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