Hebei Education Edition Grade Five Mathematics

Second, the analysis of teaching objectives

Knowledge and ability: master the area formula of parallelogram and express it with letters; Can use formulas;

Process and method: Explore the parallelogram area formula through hands-on operation, discussion and induction;

Emotion, attitude and values: experience the challenge of exploring the parallelogram area formula and realize the transformation of numbers;

Teaching emphasis: master and use the formula to calculate the area of plane quadrilateral;

Difficulties in teaching: to explore the area formula of plane quadrilateral by using the mathematical thought and method of transformation; Preparation before class; Teacher preparation

Thirdly, the analysis of learners' characteristics

The students learned the area of rectangle and square, and also learned parallelogram.

Fourthly, the choice and design of teaching strategies.

Curriculum Standard requires cultivating students' whole brain, hands-on and ability, and cultivating students' unity spirit.

Five, teaching preparation

Teachers should prepare 1 piece of rectangular and parallelogram paper with equal bottom and equal height, and 1 piece of square paper, which should not be different from rectangular paper in area. Students prepare 1~2 pieces of parallelogram paper, scissors, triangles, etc.

Sixth, the teaching process.

First, create a situation

(1) The teacher took out 1 rectangular and square pieces of paper, each of which is not suitable for intuitive viewing. First estimate which area is large, and then discuss the comparison method.

Teacher: Students, we have learned the areas of rectangles and squares. Look at the rectangular and square paper in the teacher's hand. Estimate, which area is larger?

Health 1: I think the area of a rectangle is large.

Health 2: I think the square is very large.

Health 3: I think it may be the same age.

Teacher: What method can be used to test which view is correct?

Health 1: overlapping comparison.

(The teacher's operation should be invisible. )

Student 2: Measure the length and width of a rectangle and the side length of a square, calculate their areas with formulas, and then compare them. Teacher: How about this method?

Health: OK.

T: The measured data are calculated by formulas. The teacher will tell you the data later, and we will calculate it again.

(2) When the teacher takes out rectangular and parallelogram papers with equal bottom and equal height, which area should be estimated first? Then discuss the method of comparison. Draw out what you want to learn in this lesson.

Teacher: Let's look at these two pieces of paper again. One is a rectangle and the other is a parallelogram. Tell me which area is large?

Raw 1: parallelogram paper size.

Health 2: Rectangular paper is big.

Health 3: Same size.

Teacher: What if there is disagreement?

Students may speak different ways to interact with teachers. For example:)

Health 1: comparison.

(Teachers overlap and compare. )

Health 2: Measure their side lengths.

Teacher: Can you work out the area of a rectangle? Can the area of parallelogram be calculated?

Health: No.

Health: If you know the parallelogram formula, it will do.

If a classmate talks about the method of cutting one corner of a parallelogram and splicing it to the other side, the teacher will praise it. )

Teacher: How to calculate the area of parallelogram? Today, let's discuss the calculation formula of parallelogram area. (blackboard writing: area of parallelogram)

Second, hands-on operation

Teacher: Please take out the prepared parallelogram paper, cut it open and make it into a rectangle.

Students cut and spell independently, and the teacher knows the situation. )

Teacher: Who wants to talk about how you did it?

(Possible practice:)

Health 1: First, I made a height on the parallelogram paper with triangles, cut it along the height line, divided the parallelogram into triangles and trapezoids, and translated it into rectangles.

Health 2: I also made a height on parallelogram paper, and then cut it along the height and divided it into two trapeziums. By translation, I made a rectangle.

There is no way to give birth to 2, so I won't introduce it. The teacher operates with teaching AIDS and then sticks them on the blackboard. )

Teacher: Now, let's demonstrate the process of cutting and spelling with courseware.

(The teacher explains while operating, and finally summarizes. )

Teacher: All we have to do is cut along any height of the parallelogram and translate it to form a rectangle.

Third, summarize the formula.

Teacher: Look at the rectangle we put together and think about it: What is the relationship between parallelogram and rectangle we put together?

Health 1: The area of parallelogram is equal to the area of rectangle.

Health 2: The height of parallelogram is equal to the width of rectangle.

Health 3: The base of a parallelogram is the same as the length of a rectangle.

Teacher: That's right. Then let's see if we can deduce the area formula of parallelogram from the area formula of rectangle. What is the area formula of a rectangle?

(Students say that the teacher wrote on the blackboard: area of rectangle = length × width)

Teacher: Through observation, students found that the area of parallelogram is equal to the area of assembled rectangle, the bottom of parallelogram is equal to the length of rectangle, and the height of parallelogram is greater than the width of rectangle.

(The teacher writes on the blackboard while talking:)

Area of rectangle = length × width

↓ ↓ ↓

Area and base height of parallelogram

Teacher: What is the area of parallelogram?

Health: area of parallelogram = base × height

(The teacher finishes writing on the blackboard:)

Area of rectangle = length × width

↓ ↓ ↓

Area of parallelogram = base × height

Show me the parallelogram. )

Teacher: If the letter A stands for the base of the parallelogram, H stands for the height of the parallelogram and S stands for the area of the parallelogram. The teacher said that he marked A at the bottom and H at the height. Blackboard s=)

Teacher: Who can write the letter formula of parallelogram area?

(The student said that the teacher wrote it on the blackboard:)

s=a×h=ah

Students read the alphabet formula together. )

Teacher: Students deduce the area formula of parallelogram through hands-on analysis. Who wants to talk about what conditions are needed to find the area of parallelogram?

Health: We need to know what bottom and height are.

Teacher: Yes. Now let's calculate the area of the parallelogram.

Fourth, try to apply.

Teacher: Please observe the parallelogram in the slide and tell what the data in the picture means. How to calculate their area? After the students answer, try it yourself, and the teacher will patrol. )

Teacher: Who can tell us how you did it?

Teacher: The students have finished the two questions just now well. Teacher, there is a parallelogram here. Please calculate its area.

Teacher: How do you calculate it? Why do you count like this?

(If students multiply 15 by 12 for guidance. )

Verb (abbreviation of verb) classroom practice

Teacher: Just now, we calculated the area of parallelogram with formula. Next, I solved a practical problem, looking at the parallelogram steel plate and doing it myself.

(Students calculate independently. )

4.8×3.5= 16.8≈ 17m

Continue to consolidate exercises

Discussion on this problem by intransitive verbs

Teacher: Through the operation, measurement and calculation just now, we know that the area of a parallelogram is related to its base and height. Look at the two parallelograms under discussion. Are they equal in area?

Give students time to think independently. )

Teacher: Who wants to talk about your ideas?

(Students may have two statements:)

Health 1: The base of the left parallelogram is 2.6 cm, the height is 1.8 cm, and the area is 2.6x1.8 = 4.68cm. The base of the right parallelogram is also 2.6 cm, the height is 1.8 cm, and the area is 2.6x/.

Health 2: I also agree that the areas of these two parallelograms are equal. Their base is the same line segment, their height is the distance between parallel lines, the two heights are equal, and the area of parallelogram is equal to the base multiplied by the height, so the areas of these two parallelograms are equal.

Teacher: The bases are equal. We call them equal base and equal height. We call them contour. Like this, two parallelograms with equal bases and equal heights have equal areas.

Seven: class summary

Let's review what we learned today:

1. area of parallelogram = base × height (s = ah);

2. The areas of two parallelogram with equal base and equal height are equal.