Teaching objectives:
1. Through observation, operation and comparison, we will classify triangles according to the characteristics of their angles and sides and master the characteristics of various triangles.
2. Infiltrate the mathematical ideas of classification and set in activities, cultivate students' hands-on operation ability and inductive generalization ability, and further develop students' spatial concept.
3. In the process of triangle classification, communicate knowledge and cultivate students' awareness of inquiry and cooperation.
Teaching focus:
Triangles are classified according to the characteristics of corners and sides.
Teaching difficulties:
Master the characteristics of various triangles.
Teaching preparation:
Courseware, various triangle learning tools, experimental reports, protractor, ruler, etc.
Teaching process:
Interaction before class: Contrast angles by hand.
First, create situations and review old knowledge.
1, guess, review old knowledge
Teacher: Do you like guessing games, children? Today, the teacher brought us a riddle. Guess.
Courseware demonstration:
Shaped like a mountain,
The performance of stability is firm.
The three electrodes are connected end to end,
Learning is not easy.
-Type a geometry.
The teacher asked: Good guess! How did you guess?
2. Introduce and reveal the theme
Teacher: A triangle has three angles and three sides, and its stability is widely used in daily life. You see, many friends from the triangle kingdom came today (the courseware shows: triangles of different shapes). Are they the same shape? Yes, they have different shapes and characteristics. In this lesson, we will classify them according to their characteristics (blackboard title: classification of triangles)
(Design intention: Fun quiz to attract "life" to win. Through the quiz, arouse students' intentional attention to the corners and sides of the triangle, activate students' enthusiasm for learning, and make the class interesting at the beginning. )
Second, practice and explore classification
Teacher: Children, think carefully. What do you want to classify these triangles according to? Do you have any different opinions? Yes, the classification should be carried out according to certain standards, and triangles can be classified according to the characteristics of three angles and three sides. Next, let's divide it by angle.
(a), according to the angle.
1, Teacher: The teacher put these triangles in the envelope 1 of the group leader. Before the operation, let's take a look at learning tips. Please read them.
Learning skills:
A, each team member takes out two triangles from the 1 envelope, carefully observes or compares them, measures what the three angles of the triangle are, and marks them.
B, orderly report, put similar triangles together.
C, team leader to fill in the report.
D, each group sent a representative to report.
2. Hands-on operation and cooperative classification.
3, the whole class report exchange, evaluation.
Teacher: How many categories is your group divided into? Which belong to the same category? What are the characteristics? Are there different divisions?
4, courseware display, and named according to the characteristics of various triangles.
5. To sum up, the teacher introduces the set diagram of triangle divided by angle and writes the set diagram on the blackboard.
6. Compare the similarities and differences of the three triangles.
7. Summary
(2), according to the edge
1, Teacher: We have learned to classify triangles according to the characteristics of angles. Next, we will learn triangles divided by edges. I put these triangles in the group leader's No.2 envelope. Please read the study tips before the operation. Please read.
Learning skills:
A, each team member takes out 1 triangle from the No.2 envelope and studies the lengths of the three sides of the triangle in their favorite way. What did you find?
B, orderly report, put similar triangles together.
C, each group sent a representative to report.
2. Hands-on operation and cooperation classification
3, the whole class report exchange, evaluation.
4, courseware display, and named according to the characteristics of various triangles.
5. Know the part names of isosceles triangle and equilateral triangle, and the relationship between the two bottom angles of isosceles triangle and the three inner angles of equilateral triangle.
6. Talk about isosceles triangles and equilateral triangles seen in life and show them with courseware.
7. summary.
(Design intention: "The process of autonomous learning is actually the process of teaching activities". Promoting learning through activities is the teaching direction of this section. In the activity, give students enough time and space to explore the generation process of mathematical knowledge freely and openly. Through taking a look, thinking, discussing, dividing a point, guessing and other forms of learning, we provide students with more opportunities for "mathematical dialogue", and strive to make students really move, fully demonstrate and learn by doing, so as to understand the characteristics of triangles' sides and angles, and then learn to classify triangles, promote students' ability of classification, generalization, reasoning and hands-on operation, and make students realize the true meaning of mathematics in the process of activities. )
Third, consolidate exercises and improve internalization.
1, guessing game
Teacher: hide the triangle, only one corner is exposed. Can you guess what kind of triangle it is (Courseware presented separately: showing right angle, obtuse angle and acute angle)
Follow-up: How did you guess?
2. Draw a triangle you like in the dot diagram.
Projection display introduces what a triangle is and what a triangle is.
Design intention: practice in various forms and levels, and try to bring students into an activity field, a thinking field and an emotional field! Students travel in this field, gradually internalize knowledge, increase their wisdom and improve their ability. )
Fourth, the whole class summarizes and extends after class.
1. What did you gain from this class? Tell me about it!
2. Complete question 5 on page 87 of the textbook.
3. Make beautiful patterns with triangles.
(Design intention: By summarizing the essentials, help students master knowledge, improve their cognition, have a more comprehensive and profound understanding of triangles, and then extend knowledge from classroom to extracurricular, effectively communicate mathematics with life, realize a big society in a small classroom, and realize the application value of mathematical knowledge in life. )
More related hot articles are recommended to read:
1. Optimized teaching design of "graph grouping" in senior one mathematics.
2. Excellent teaching design of the area and area unit in the second volume of the third grade mathematics.
3. The teaching design of the second volume "Classification of Triangle" in the fourth grade mathematics.
4. Optimized teaching design of "area and area unit" in primary school mathematics.
5. Excellent teaching design template of "Preliminary Understanding of Division"
6. "Grape Valley" boutique teaching design template
7. Teaching design of the second volume "Classification and Arrangement" of Grade One Mathematics
Optimal teaching design of "triangle classification" in primary school mathematics