Teaching objectives:
1, let students understand that some things are certain to happen, some things are impossible, some things are possible, and the possibility of occurrence is large or small, which can be expressed by scores.
2. Combining with life examples, further let students experience the mathematical problems in life.
Teaching emphasis and difficulty: let students experience the specific process of the experiment and the possibility of something happening.
Teaching preparation: 1 white ball, 3 yellow balls, red and green pencils, etc.
Teaching process:
I. Information and introduction
1, teacher's description, situation: Celebrating the "June 1st" party, the teacher asked everyone to perform a program in the form of singing, dancing, cross talk, sketch, etc. Draw lots to decide.
Xiaohua thought before drawing lots: I am a golden voice, so I'd better smoke a song. ...
2. Discussion: Will Xiaohua get what she wants? Why?
[Comment]: Leave room for students to invent, let students use their brains to capture the phenomena in life, closely combine what they have learned with real life, and deepen their understanding of mathematical knowledge. This situation is experienced by students themselves, so they know that Xiaohua may not sing, but it is unlikely to be picked, because only one of these signs is singing, which naturally leads to the topic: possibility.
3. Summary: In our life, some things are inevitable, some things are impossible, some things are possible, and the possibility of occurrence is great or small. Today we are going to learn about this possibility.
Second, experimental exploration.
1, touch the ball.
Activity rules: Prepare 3 yellow balls and 1 white ball with the same size, and put them into the bag to stir.
(1) deskmate activities. Each person touches 10 times, one ball at a time, then puts the touched ball in, touches it for the second time after stirring, and touches it for the third time ... Fill in the statistics table of 20 touches (you can use the word "positive").
(2) Students work in groups.
(3) Observation: Is the result of the first experiment the same as the predicted result?
(4) In groups of four, fill in the statistical table of 40 touches.
(5) Observation and discussion: Is the summarized result close to the predicted result?
(6) Summary: The more times you touch, the closer the result is to the predicted result.
[Comment]: This activity embodies the learning style of "hands-on practice, independent exploration, cooperation and exchange", and students gain knowledge through practice.
2. Practice 1-4 on page 89 of the textbook.
(1) Students think independently and practice.
(2) communicate in groups, discuss the learning situation and explain your reasons.
Third, expand and extend.
1. Mark three numbers 1, 2, 3 on a cube to meet the following requirements: the probability of number 1 and number 2 are both 1/6, and the probability of number 3 is 2/3.
2. Lucky draw.
There are four red pencils and two green pencils in the box. Please tell me what color pencil you want to touch first. What are the possibilities? Then touch it in the box. If the color and touch are the same, you can take this pencil.
There are three identical pens in the box: red, blue and black. If you take out two pens at random, how many kinds of results may appear?
[Comment]: This is an activity that students are interested in. It is both interesting and challenging, and provides students with sufficient development space.
Summary: What did you gain from this class?
[General comments]
The key of this course is to pay attention to students' learning process. Teachers create an educational atmosphere conducive to students' lively development, and teachers really become organizers, guides and collaborators of teaching activities. Judging from the actual teaching effect, students are active in learning and always sparkle with innovative thinking.