Methods and procedures

1. Explore the positional relationship between a straight line and a circle, the quantitative relationship between the distance d from the center of a circle to a straight line and the radius r of a circle, and experience mathematical activities, which is full of exploration and challenges.

2. Only through independent exploration, cooperation and exchange, and daring to express their views, can we benefit from the exchange.

3. The knowledge in this section will be used to solve related problems and improve the ability of observation, exploration, induction and generalization.

Knowledge and skills

Understand the three positional relationships between straight lines and circles, and master the nature and judgment methods of the positional relationship between straight lines and circles.

Emotional attitudes and values

Through observation and analogy, we can understand the relationship between things and the dialectical unity of motion changes; Cultivate a scientific attitude of seeking truth from facts and the spirit of collaborative research.

Second, the teaching preparation:

1. Teacher preparation: Build a teaching platform for students in the network classroom of the campus network. Use geometry

Making geometry courseware with sketchpad to explore the positional relationship between straight line and circle; Provide students with multimedia resource library and test question bank; Open a special learning website to expand students' after-school challenges.

2. Students' preparation: Review the position relationship between the point and the circle, and preview the knowledge of this lesson.

Third, autonomous learning design:

Learning is the process of acquiring knowledge. Constructivism holds that knowledge is not acquired by teachers, but by learners in a certain situation, that is, social and cultural background, with the help of others (including teachers and learning partners) and necessary learning materials, through the way of meaning construction. On the basis of this theory, this section adopts? Scaffolding teaching method? . First of all, build a platform for students to explore problems. Students can obtain the positional relationship between straight lines and circles and their judgment methods through analogy and exploration experiments.

(A) the description of learning content and learning tasks

Through observation and hands-on, we can understand the positional relationship between straight line and circle and its judgment method.

Emphasis: the positional relationship between a straight line and a circle and the quantitative relationship between the distance from the center of the circle to the straight line and the radius of the circle, especially in the case of tangency.

Difficulties: Explore the positional relationship between a straight line and a circle, and the quantitative relationship between the center of the circle and the distance and radius of the straight line, and use it to solve related problems.

(B) Analysis of learner characteristics

Junior high school students are active in thinking and curious. They are innovative, bold, willing to experience and easy to accept new challenges. However, due to the limitation of knowledge, their abstract thinking ability is not good. Therefore, teachers need to build an operating platform in teaching, so that students can feel the pleasure of acquiring knowledge through personal experience.

Fourth, teaching design ideas:

1. Teaching ideas: This course allows students to operate the geometric sketchpad platform built by teachers themselves under the network environment by analogy of the positional relationship between points and circles and by studying problems, and explore the methods of predicting the positional relationship between straight lines and circles and judging them.

2. Teaching multimedia design:

Table 1? Subject participation? Teaching multimedia design table

Five, teaching process design and analysis:

Table 2 the positional relationship between a straight line and a circle? Subject participation? Teaching process and analysis table

Six, blackboard design: