teaching process

First, create situations and introduce new lessons.

1. Teacher's question: In daily life, we often encounter some math problems, such as: it takes 8 minutes to cook one egg, and how long does it take to cook five eggs?

Generate 1 by default: cook one by one, one for 8 minutes, and five for 40 minutes.

Default second generation: put 5 eggs into a pot and cook them together, which takes 8 minutes.

2. Ask again: Why do you want to cook together?

3. Teacher's summary: It saves time and effort to put five eggs into the pot and cook them together. It seems that cooking eggs should pay attention to methods! There are still many such problems in life. Let's study one of them-the "pancake problem" which also needs to pay attention to methods. Blackboard: Pancake problem.

Design intention: create a life-like teaching situation to stimulate students' interest in learning. At the beginning of this class, I started from the simple case of "boiling eggs" in life, mobilized students' existing life experience, and guided students to review how to arrange their homework reasonably to save time, so as to prepare for the infiltration of optimization ideas in new knowledge teaching.

Second, explore independently and explore branding methods.

(1) Read the information and understand the pancake rules.

1. Courseware presents the theme map. Guide the students to observe and find the key mathematical information: only two cakes can be baked at a time, and both sides should be baked for 3 minutes.

2. Teachers ask questions, guide students to think, and let students deeply interpret mathematical information;

(1) What do you mean you can only bake two cakes at a time? Guide the students to understand that only two cakes can be baked at a time, which means that at most two cakes can be put down in the pot at the same time. If there is only one cake, you can also put only one. )

(2) Do you want double branding? Cake should be branded on both sides. ) The teacher stressed: For the convenience of expression, we can call the first brand face positive and the second brand face negative.