Knowledge points of "preliminary understanding of the corner" in the second grade of primary school
First, the understanding angle 1. Characteristics of an angle: a vertex and two sides (straight)
2. The size of the angle is related to the size of both sides, and has nothing to do with the length of both sides.
3. The angle of painting:
(1) Fixed Vertex.
(2) Draw a straight line from this point.
(3) Draw another side (at right angles, aim at the drawn side with the right angle side and draw a line along the other right angle side).
Second, the classification of angles:
1, understanding right angles: the characteristics of right angles,
2. Know acute angle and obtuse angle: acute angle is less than right angle, and obtuse angle is greater than right angle.
3. You can judge the right angle, acute angle and obtuse angle with a triangular ruler: overlap the vertex of the right angle on the triangular ruler with the vertex of the compared angle, then overlap one side of the right angle on the triangular ruler with one side of the compared angle, and finally compare the other side of the right angle on the triangular ruler with the other side of the compared angle. This line is a right angle, the inside is an acute angle and the outside is an obtuse angle.
Teaching plan of "preliminary understanding of the corner" in grade two and two.
Guiding objective: 1. Let the students know the angle, judge the angle and know the names of each part of the angle by combining the life situation and operation activities.
Through learning, I understand that the angle is related to the size of the side opening, but not to the length of the side.
3. Learn to draw angles with a ruler at first.
4. Cultivate students' practical ability and realize that mathematics comes from practice and the spirit of unity and cooperation.
The main points of learning guidance:
Know the angle, know the names of each part of the angle, and learn to draw the angle with a ruler.
Difficulties in guiding learning:
It is preliminarily recognized that the angle is related to the size of the openings on both sides, but not to the length of the sides.
Teaching aids and learning aids:
Teaching AIDS: electronic whiteboard, a triangular board and a movable corner.
Learning tool: triangle, adjustable angle.
Learning guidance process:
First, create a situation
Teacher: Rabbit invited our classmates in Class Two (2) to visit their new house. Do you want to go?
Health: Yes.
Teacher: What's the shape of the house?
Health: Triangle, rectangle, square.
Screen display: pull out triangles, rectangles and squares from the house, and then flash corners of rectangles, squares and triangles respectively.
Introduction: Kid, what was that flashing figure just now? Do you know that?/You know what? Today, we will make friends with Jiao of this class.
Blackboard writing: cognitive perspective
[Design concept: By introducing scenes, create a vivid home for the white rabbit, and help the white rabbit find out what graphics make up its home? Let students study in a relaxed situation, and their childlike innocence can fully arouse students' interest and enthusiasm in learning.
Second, pre-learning
1. Corners are hidden not only in the graphics, but also in the campus. Can you find some corners from the campus graphics? (Show campus theme map)
Let the students talk about where there are corners first, and then demonstrate them in the courseware.
Encourage students: Students are really eager to find so many corners.
There are speakers on campus. There are many places and horns in life. Can you still find them?
Show the pictures in the courseware: scissors, straws and faucets.
The teacher concluded: horns seem to be everywhere in our lives.
[Design concept: use familiar life, scenes and common objects in daily life in the theme picture to attract students' attention, so that students can abstract what they have learned from observing objects, let students experience the process of mathematical knowledge from concrete to abstract, feel the authenticity of mathematical knowledge, and initially experience the mathematical knowledge of the angles around us in the process of finding angles. ]
3. show me the guide
① Find it: Take out the triangle, find one of the angles, and carefully observe what parts this angle is made of.
② Drawing: Try to draw a corner and tell me how you draw it.
③ Change: Is there any good way to make the angle bigger and smaller? What did you find?
4, group cooperative learning, teacher guidance
Third, learn from each other.
Communicate with the whole class and sort out blind spots
Cognitive angle:
(1) Look at the first self-study tip.
Teacher: How do you feel when students take out their triangles and touch them?
Health: keenness
Teacher: The cusp is the apex of an angle.
Blackboard: Vertex
Teacher: How do you feel when you touch these two lines from the vertex again?
Health: Straight man.
Teacher: These two straight lines are called the sides of the corner.
Blackboard writing: edge
(2) Teacher's summary: A corner consists of a vertex and two sides.
Draw while talking.
pinnacle
(sharp) edge (straight)
(3) Learn the painting angle
Teacher: We have learned a lot about horns. Do you want to know how the corners are drawn?
Who wants to draw a corner on the blackboard?
Point out the names and draw corners. Other students draw corners in the draft book.
Teacher: Would you like to tell other students how to draw corners?
Courseware: Draw () first, then ().
Note: Draw an arc between two sides to mark the angle.
[Design concept: Drawing corners is the teaching focus of this course. Let students draw by themselves and adopt the method of "letting go" before "helping", which not only develops students' self-study ability, but also stimulates students' strong interest in learning. At the same time, through the form of competition, once again strengthen students' understanding of the method of drawing corners, so that they can experience the joy of success in the exhibition evaluation]
(4) the size of the angle
Teacher: The teacher has a horn in his hand. What can the students do to make it bigger?
Four students are in a group. Let's discuss how to enlarge the angle of this activity.
Health: I take out the notes on both sides, and the angle becomes larger.
Teacher: The angle is getting bigger. Where is the angle getting bigger? Can you point it out with your finger?
The teacher pointed to ask: the angle has become bigger, has the edge changed?
Teacher: On the contrary, what else can you do to make the angle smaller?
Health: If you put the notes on both sides together, the corners will become smaller.
Teacher: Can you point out which corner is smaller?
When I use my finger, the angle becomes smaller. Has the edge changed?
The teacher used the activity angle to demonstrate: the teacher took an activity angle, and after it gradually became larger, he subtracted a few pieces of paper from both sides and looked at the edge of the angle. Has it changed?
(5) Debate between Red Corner and Blue Corner
Design intention: In this teaching, by pulling the activity angle, we can experience the relationship between the size of the angle and what it is. In the concrete operation, students can fully perceive, enhance the cognitive effect and cultivate their spatial concept.
(6) The summary of children's songs is helpful for memory.
The small corner is really beautiful; Two sides of a vertex.
Never forget to draw a corner; Draw vertices first, then draw edges.
How to distinguish the size of the angle; Just look at the mouth, not the side.
Fourth, the evaluation of learning.
1, judging the angle (see courseware)
2. Create a new home for the situational rabbit, and then find the angle completely.
3. Count: How many angles does a * * * have?
4. Swing a corner with a small stick: How many small sticks does it take to swing a corner? Do you have any other methods?
Reflections on the Teaching of "Preliminary Understanding of Corner" in Grade Three and Grade Two of Primary School
The Preliminary Understanding of the Corner is a traditional textbook. Because the new curriculum reform advocates the teaching concept of students' cooperative inquiry and independent learning, I designed activities for students to discover their own knowledge when preparing lessons. The class is divided into three parts. The first part is the introduction. On the basis of the original understanding of graphics, students place graphics with wooden sticks. When they are placed in a triangle, they ask: What is another back figure? In order to introduce the learned materials naturally. The second part is the activity practice and summary. The third part is practice. The second part is divided into several parts, such as finding the corner in life, making the corner according to your own diagonal feeling, summarizing the characteristics of the corner and drawing the corner in combination with textbooks and practice. It fully enables students to operate, explore knowledge and learn independently in cooperation, embodies the spirit of the new curriculum standard, and is also the most important part of the whole class, which can best test teachers' contingency potential and familiarity with teaching materials. Because it is difficult for teachers to predict what problems students will have in practice. In teaching, I dealt with unexpected situations in a timely and flexible manner, without stiffly drawing students back to my teaching plan. For example, in the process of letting students make their own corners, some students use two pieces of hard paper to make three different "corners", one is an ordinary corner, the other is a cross-shaped corner and the other is a T-shaped corner. Some students there don't understand how many corners they have made, but only think that one corner is made by themselves, and some are discovered and created by themselves. At this time, the teacher should make the best use of the situation, let the students say which corner he refers to first, ask a corner, and if there is anything else, can you draw it for everyone to see? And give praise in time, which can not only encourage their intentions, but also consolidate their diagonal understanding, killing two birds with one stone.
The new curriculum reform has brought many new teaching ideas to teachers, and teachers have also adopted many new methods in teaching, and created many situations according to them. But this is not enough. We should always be aware of the importance of students' independent participation, experiential learning, independent learning and independent thinking, so that students can really participate in the learning process and think, do, communicate, discover and acquire knowledge from their own success or failure experiences. This kind of study is intentional and valuable.