1, simulate the process of pancake making by operating learning tools, so that students can understand the idea of overall planning, understand the meaning of overall planning, master the overall planning method of pancake making, and apply it in practice.
2. Improve students' ability to explore and solve problems in learning activities such as question inquiry, hands-on simulation, exchange and debate. In the exploration of laws, students' observation ability and independent thinking ability are cultivated, and their thinking is developed.
3. Make students realize the value of communication and debate as a learning method through communication and debate activities.
Prepare a big circle (pot), 9 small circles (pancakes) and a set of multimedia courseware for teaching AIDS.
Learning tools Prepare one learning tool for every two students, including one big circle and nine small circles, and four experimental records.
teaching process
First, the scene import:
First, cut to the chase
1, show directly (pot and cake): What is this? What can these two things do together?
2, Jieti: Today we will learn the pancake problem (blackboard writing: pancake problem)
Second, explore new knowledge
1, show the question and understand the meaning.
Five customers came to the pancake shop near the railway station, each of whom wanted to buy a pancake and was in a hurry to catch the train. The limited time should not exceed 15 minutes. It takes 3 minutes to bake both sides of a pancake, and only two pancakes can be put in the pancake pan in the shop at a time. Students, do you think these three customers can eat pancakes?
(1) birth conjecture
(2) Teacher: Can it be? First of all, we have to understand the meaning of the question. Excuse me:
What do you mean by "it takes 3 minutes on both sides"? Please make a gesture. So how many minutes does it take to bake a cake?
What do you mean by "you can only put two cakes at a time"? Please make a gesture. So how many minutes does it take to bake two cakes?
(3) If 1 piece of cake is cooked, how many minutes (6 minutes) will it take at least?
Why is it 6 minutes (3 minutes for heads and 3 minutes for tails)?
(4) If you want to bake two cakes, it will take at least a few minutes (6 minutes).
What do "2" and "3" mean in 2×3=6 (points)?
Teacher: 1 cake takes at least 6 minutes, while baking two cakes should take 12 minutes. What's the matter?
(Because one pot can bake two cakes at the same time)
2, explore the "grouping flipping"
(1) How to brand the four cakes (what does the "4" in 4×3= 12 (points) mean)
(2) Introduce the method of "grouping flipping"
(3)6 sheets, 8 sheets, 10 sheets ... How long does it take to brand?
(4) Feedback: What did you find?
3, explore the "take turns flipping"
(1) Teacher: If you bake three cakes, what is the most time-saving way?
(2) independent thinking, teamwork branding.
1) Please think about it quietly. How are you going to brand it? How many minutes did it take? Is it the least time?
2) After you have an idea, first brand it by yourself with the materials sent to you by the teacher, and then tell the process of branding gently at the same table in your own language.
Teacher: Think about how I can report to my classmates so that everyone can understand.
(3) Feedback communication: named students answer:
Health 1: 2 pieces+1 piece, 6 points +6 points = 12 points (let life play)
Student 2: Oral performance: 3②→ 3 minutes → ② Take it off.
③①→3 minutes → ③ All right.
①②→3 minutes → ① ② All right.
Teacher: Who understood the name-named student 3 once again? The teacher directed the oral process.
(4) deskmate cooperation, start work with learning tools flipping a flipping.
Please use this classmate's method just now to brand it, calculate it, and verify whether it takes 9 minutes.
(5) Teacher: Please compare these two different branding methods. Why does branding method 2 save time?
Ask each student to think quietly and compare the two methods. Why (think independently)?
(2) report. According to the reporter's summary:
Flipping method 1 The second time, only 1 piece of cake is put, which is too wasteful. Flipping method 2 is to bake two cakes at the same time every time, which is not wasteful. It seems that when we bake cakes, we try to make two cakes in the pot bake together, which will not waste time and save the most time. That is to say, when we solve problems at ordinary times, different problems should be solved in different ways, and its effect is good.
(6) Name the branding method 2
Teacher: There are so many mathematical mysteries in flipping method 2. Can you give her a name (alternately flipping, alternately flipping)?
4, explore the "grouping flipping+taking turns flipping"
(1) If you bake 5 cakes, how to bake them in the shortest time? Who will introduce the method?
(2) Introduce the method of "grouping branding+taking turns branding"
(3) Will you solve it now?
Five customers came to the pancake shop near the railway station, each of whom wanted to buy a pancake and was in a hurry to catch the train. The limited time should not exceed 15 minutes. It takes 3 minutes to bake both sides of a pancake, and only two pancakes can be put in the pancake pan in the shop at a time. Students, do you think these three customers can eat pancakes?
(4) How to burn 7 pieces of woolen cloth and 9 pieces of woolen cloth 1 1 woolen cloth in the shortest time?
A, work together at the same table and write the results on the exercise paper.
B, feedback: What did you find (how did you come up with it so quickly, is there any good way)
(5) What time-saving method is used to bake 12 cakes? Why?
(6) In what case do you think grouping saves time and combining the two methods saves time?
Third, the development time
1, a pot can bake three cakes at the same time, and it takes three minutes to bake each side. How long does it take to bake six cakes at least?
2. One pot can fry two fish at the same time, and each side needs to fry for 5 minutes. How long does it take to fry three fish at least?
Fourth, the class summary
Teacher: What do you want to say after learning this lesson today?
Fifth, expand and extend
Puzzle: If this pot can bake 10 cakes at a time, but now there are 15 cakes to bake. Please think about how long it will take.
Teaching reflection:
"Mathematical Problems in Pancakes" is the content of Mathematics Wide Angle in Book 7 of the textbook of People's Education Press. In addition to teaching students knowledge, what should be left for them through teaching? I think it is important how to make pancakes and the laws contained in them, but this is only the category of knowledge and skills. I don't want to stay at the level of teaching knowledge only. What is more important than knowledge is the mathematical ideas and methods contained in them. These are the sustainable development of students. Life-long development is the most important thing. This class is based on cultivating students' good thinking ability, starting from students' life experience and knowledge base, creating problem situations. According to the new curriculum standards, students can experience the process of exploring mathematical knowledge in "pancake" with the help of learning tools, gradually master the method of pancake, and initially realize the application value of mathematical methods and optimize their ideas in solving problems.