Judges and teachers:

Hello! Today I'm going to talk to you about the topic of "rectangle judgment". Based on the concept of the new curriculum standard, corresponding to this section, I will explain what to teach, how to teach and why to teach like this from four aspects: textbook explanation, teaching purpose explanation, teaching strategy explanation and teaching process explanation.

A, teaching material analysis (textbook):

1, the position and function of teaching materials: this section of teaching materials is the second volume of junior high school grade one, and the quadrilateral section 2 in chapter 19 is one of the important contents of junior high school teaching. On the one hand, this is a further deepening and expansion of inequality on the basis of learning inequality; On the other hand, it lays a foundation for learning inequality groups and other knowledge, and is a tool for further studying inequality. Therefore, I think this plate plays a connecting role.

2. Teaching objective: 1. Through exploration and communication, let students gradually get a rectangular judgment method, let students experience the process of knowledge development, and solve related problems with judgment methods. 2. By means of guessing, analyzing, analogizing, measuring, communicating and displaying, let students fully experience the process of drawing conclusions, learn to analyze in observation, learn to perceive in operation, learn to cooperate in communication and learn to listen in exhibition. Cultivate students' rational reasoning ability and logical thinking ability, and let students learn to learn in learning. 3. Let students experience the process of exploring rectangular judgment and the methods of exploring and studying problems, so that students can have a successful experience in mathematics activities and enhance their self-confidence.

3. Teaching emphasis and difficulty: teaching emphasis: mastering the judgment method and proof process of rectangle; Teaching difficulty: the proof and application of rectangular judgment method.

In order to clarify the key points and difficulties, so that students can achieve the teaching objectives of this class, I will talk about teaching methods and learning methods:

Second, teaching strategies (teaching methods):

1, teaching method: through hands-on practice, cooperative inquiry and group communication, students' abilities of logical reasoning and hands-on practice are cultivated.

2. Teaching methods and theoretical basis: Through exploration and communication, the rectangular judgment theorem is gradually obtained, so that students can experience the process of cognition and use the theorem to solve related problems. Try to find solutions to problems from different angles through open-ended propositions.

Third, the teaching process

Link 1: Create situations and introduce new lessons.

Who can tell me how to define a rectangle through the study of rectangles in the last class? By reviewing the definition of rectangle, it is concluded that there are other ways to introduce new lessons besides defining rectangle. )

Review: 1. Definition of rectangle: A parallelogram with a right angle is called a rectangle. 2. Properties of rectangle: Opposite sides: The opposite sides are parallel and equal. Diagonal: The four angles are equal and all are right angles. Diagonal lines: bisected and equal to each other. 3, the nature of parallelogram:

Properties of parallelogram; Parallelogram judgment.

The two groups of opposite sides of parallelogram are equal respectively.

Parallelogram Two groups of opposite sides are parallel, and two groups of opposite sides are parallel (or equal).

A set of opposite sides of a parallelogram are parallel and equal.

A set of parallelograms whose opposite sides are parallel and equal is a parallelogram.

Quadrilaterals whose diagonals bisect each other are parallelograms.

A parallelogram is a parallelogram with two equal diagonal lines.

Step 2: Try to discover and explore new knowledge: Activity 1: Divide the students into study groups and try to judge whether the quadrangular cardboard prepared before class is rectangular cardboard with the protractor in your hand, and explain the reasons. The solution to this problem is in the form of group cooperation and communication. In the process of inquiry, students accumulate knowledge and get the first judgment theorem of rectangle-the definition of rectangle. Teachers go deep into the group as collaborators, communicate with students, understand the students' inquiry process and give appropriate guidance. ) After the activity, the group representatives report the communication results, and can write on the blackboard appropriately to push the card and explain. In this process, all students can complement each other and evaluate each other, and cultivate students' language expression ability and reasoning ability.

Activity 2: Divide the students into study groups and try to judge whether the parallelogram cardboard prepared before class is rectangular cardboard with only one ruler, and explain the reasons. The solution to this problem is still in the form of group cooperation and communication. In the process of inquiry, students can accumulate knowledge and get the second judgment theorem of rectangle-the first judgment theorem of rectangle. ) Through this interactive process, all students can participate in it, gain different degrees of gains and experience the joy of success.

After the theorem 1 and theorem 2 are obtained, three methods for judging rectangles are summarized, and the types of questions are compared and distinguished, so that students can further clarify the conditions for applying theorems. (Students compare and summarize. )

Link 3: Apply the discriminant and consolidation theorem.

Summary: The rectangular judgment method 1 has a parallelogram with right angles, and the rectangular judgment method 2 has a quadrilateral with three right angles.

Rectangle judgment method Three parallelograms with equal diagonals are rectangles. In order to help students consolidate and apply the theorem, the exercises are as follows:

1. True or false: 1. A quadrilateral with four equal angles is a rectangle. 2. A quadrilateral with equal diagonals is a rectangle. 3. A quadrilateral whose diagonal is bisected and equal is a rectangle. 4. A set of diagonally complementary parallelograms is a rectangle.

Second, fill in the blanks:

1. If the diagonal AC and BD of quadrilateral ABCD are equal and divided into O, then quadrilateral ABCD is _, if ∠AOB=60, then AB: AC = _, if AB=4cm, BC=_cm, and the area of rectangular ABCD is _.

2. Two parallel lines are cut by a third straight line, and the quadrilateral formed by the intersection of two groups of bisectors at the same side inner angle is _. Principles of problem setting and explanation of solutions:

The design of judgment questions strengthens students' understanding and mastery of the theorems they have learned, enables students to transform the given conditions into the conditions needed for applying the theorems, and discriminates the setting of judgment questions in order to better apply the theorems. Fill in the blanks The first question is the adaptation of textbook example 2, and the second question is the adaptation of textbook exercises. These two problems are solved by the learned theorems respectively, so that students can learn to be practical. The solution to these two problems is to do it independently first. Students who have difficulties can ask teachers or classmates for help, and students can help each other to finish, and send students to explain on the blackboard.

Link 4: Open training, divergent thinking.

Variant training

As shown in the figure, in △ABC, point O is a moving point on the side of AC.

Let the intersection o be a straight line MN∨BC, and MN intersects ∠BCA.

The bisector is at point E, and the bisector of the outer corner of ∠BCA is at point F.

(1) Verification: EO=EF(2) Where does the quadrangle AECF move? Is it a rectangle? And prove your conclusion.

Variant training is designed to distract students' thinking and make students at different levels gain something. Sports, rotation and other issues are also hot spots in the senior high school entrance examination in recent years. After the students have finished thinking and discussing, the teacher will give appropriate guidance and explanation.

The fifth step: reflect on the summary and experience the harvest. What did you learn today? Talk about your gains. Reproduce knowledge, teacher comments, actively help students in the lecture hall, think boldly, accept affirmation and put forward hope.

Key six: assign homework, feedback feedback, grasp the results of what you have learned through homework feedback, further consolidate the theory and apply theorems.

The above is my better understanding and elaboration of this lesson. Please correct me if there are any shortcomings. I will continue to work hard, thank you!

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