The meaning and basic nature of proportion.

Writing ideas: write down the teaching objectives, teaching priorities and difficulties about proportion.

Teaching objectives:

1, understand the meaning of proportion, know the names of various parts of proportion, and initially understand the difference between ratio and proportion; Understand the basic nature of proportion.

2. According to the meaning and basic nature of proportion, we can correctly judge whether two proportions can form a proportion.

3. Cultivate students' ability of analysis and generalization and the spirit of being brave in exploration through independent inquiry, observation and comparison.

4. Through autonomous learning, students can experience the happiness of success in the process of inquiry.

Teaching emphases and difficulties:

Key points: Only by understanding the meaning and basic nature of proportion can we correctly judge whether two proportions can constitute a proportion.

Difficulty: the basic nature of self-exploration ratio.

Teaching preparation: CAI courseware

Teaching process:

First, review and import

1, Dialogue: Students, we have learned something about comparison. How much do you know about comparison? Answer: meaning, names of parts, basic nature, etc. )

Remember how to find the ratio?

2. Courseware presentation: Calculate the ratio of the following two ratios in each group.

⑴ ? 3:5 ? 18:30 ? ⑵ ? 0.4:0.2 ? 1.8:0.9

⑶ ? 5/8: 1/4 ? 7.5:3 ⑷ ? 2:8 9:27

Comments: Starting from students' existing knowledge and experience, preparing lessons is convenient and quick.