1. On the basis of understanding, master the calculation formula of parallelogram area and correctly calculate the area of parallelogram;

2. Through operation, observation and comparison, develop students' concept of space, infiltrate the transformed thinking method, and cultivate students' ability to analyze, synthesize, abstract, summarize and solve practical problems.

Teaching emphasis: master the area calculation formula of parallel four sides and use it correctly.

Teaching difficulty: derivation of parallelogram area calculation formula.

teaching process

First, situational introduction

1. Play the video of the successful launch of the rocket carrying the "Chang 'e-1" lunar exploration satellite.

2. Teacher: In order to commemorate this meaningful moment, the children in our school used some graphics to spell out the rocket model carrying "Chang 'e-1" in math activities!

3. (The courseware shows the assembled model) Let the students observe what graphics the rocket model is made of.

Question: If you compare the sizes of these figures, what should you know about them? What graphic areas have we learned? How to ask?

4. Comparing rectangle and parallelogram, who has a large area and who has a small area, what method can be used? Guide the students to say how to count squares. )

Second, count.

Compare the sizes of two graphic areas by calculating a square.

(1) Requirements: each square represents 1 cm2, and less than one square is counted as half a square.

(2) Students use the square method to calculate the area of two figures and make records.

(3) Feedback the reported results, and draw the conclusion that the two graphs have the same area through several squares.

(4) Question: If the parallelogram is large, it is troublesome to count squares. Can you find a method to calculate the area of parallelogram?

(5) Observing the recorded data, what did you find?

(6) Guide students to communicate, find out and get feedback from the whole class: the base of parallelogram is equal to the length of rectangle, the height of parallelogram is higher than the width of rectangle, and the area of parallelogram is equal to the area of rectangle.

(7) Propose a conjecture: the area of parallelogram = base × height.

Third, fight and do it.

(1) Put forward the requirements: cut and put together with a triangular ruler and scissors, try to turn the parallelogram into a figure we have learned about area calculation, and then exchange our methods with the students in the group.

(2) Students operate in groups and teachers patrol for guidance.

(3) Students show different ways to change a parallelogram into a rectangle.

(4) The teacher demonstrates the process of transforming parallelogram into rectangle with courseware. Ask students to observe and think about the following two questions:

A. What's the change compared with the original parallelogram? What hasn't changed?

B what is the relationship between the length and width of the spliced rectangle and the base and height of the original parallelogram respectively?

(5) exchange feedback and guide students to draw;

A. the shape has changed, but the area has not changed.

B the length of the assembled rectangle is equal to the base of the original parallelogram, and the width is equal to the height of the original parallelogram.

According to the rectangular area formula, the parallelogram area formula is obtained and expressed by letters.

(6) Activity summary: We transformed the parallelogram into a rectangle with equal area, and obtained that the area of four parallel sides is equal to the base multiplied by the height by using the rectangular area calculation formula, which verified the previous conjecture.

Fourth, consolidate practice.

(1) (Example 1) The parallelogram flower bed is 6 m long at the bottom and 4 m high. What is its area?

(2) Students independently complete and feedback the answers.

Verb (abbreviation of verb) course summary

What did you get from this lesson? (Students are free to answer. )

Distribution of intransitive verbs

1. Ask students to complete the exercises in the textbook;

2. Observe the quadrangle in life, measure and calculate its area.