Teaching objectives:

1. Understand and master the concept and properties of the triangle midline, and use the properties of the triangle midline to solve related problems.

2. Experience the process of exploring the nature of the triangle midline, so that students can experience the learning process of hands-on practice, independent exploration and cooperation and exchange.

3. Through the exploration and research of problems, cultivate students' ability to analyze and solve problems and the flexibility of thinking.

4. Cultivate students' scientific spirit of bold conjecture and reasonable argumentation. Teaching emphasis: explore and apply the nature of triangle midline.

Teaching difficulties:

Solve related problems with transforming ideas. Teaching methods: creating situation-establishing mathematical model-applying-expanding and improving teaching process: creating situation: measuring the distance between two unattainable points.

Exploration activities:

Activity 1: paper-cut puzzle. Operation: How to cut a triangular piece of paper into two parts and make the two parts combine into a parallelogram. Observe and guess: What is quadrilateral BCFD? Inquiry: How to explain that quadrilateral BCFD is a parallelogram?

Activity 2: Explore the nature of the triangle midline. Apply exercises and solve situational problems.

Examples Teaching

Operation-speculation-verification

Development: Mathematics Laboratory

Summary: homework: p 134/ exercise 3.6 1 3.