1. Contextual introduction of new knowledge.
Teacher: Hello students, please take a seat.
Teacher: Students, please see the big screen, what mathematical information have you found?
Teacher: You are the first to raise your hand, please speak. The 5th anniversary of the department store is celebrated, and the electrical appliances are 10% off, and other goods are 85% off. Teacher: You have observed it very carefully.
Teacher: Then what does it mean to have nine or five folds?
Teacher: Seeing everyone frowning, it's okay, teacher, let's explain.
Teacher: Stores sometimes reduce the price of ** goods, which is called a discount. A few folds means a few tenths, that is, tens of percent. Teacher: For example, 9% off is 90% of the original price**
Teacher: So, now everyone knows what 85% off means.
Teacher: Well, I heard everyone say in unison that 85% off is 85% of the original price. People really apply what they have learned.
Teacher: When we are on sale, we will buy goods more affordably. Today we will learn about Xi discount (board book discount).
2. Enlightenment and induction, ** new knowledge.
Teacher: Please see the first question on the big screen, what do you know from the question?Teacher: Dad bought a bicycle for Xiaoyu, the original price was 180 yuan, and I bought it at a discount of 85%.
Teacher: Your voice is so loud. The meaning of 85% off is 85% of the original price. Teacher: So, students, how much did Xiaoyu's bicycle cost?Teacher: Do you know how to answer the questions?Please communicate with each other at the same table. Teacher: Well, seeing that everyone has done a good job, it seems that there is an answer. Teacher: The boy in blue in the middle, please, please speak. Teacher: Your column formula is 180*85%Teacher: Why is it like this?
Teacher: Because the 85% discount is 85% of the original price**, and the original price is 180 yuan. Teacher: In other words, it translates into a question of what is 85% of 180.
Teacher: Then the discount problem of finding the current price can be calculated by multiplication, and there is a quantity relation: the current price = the original price * the discounter: So what is the result of your calculation?Teacher: Well, it's 153 yuan.
Teacher: The current price can be multiplied by the original price, so that we can get the ** of the light rain bike. Teacher: Do other students also calculate in this way?
Teacher: Well, it seems that such a simple issue of discount is difficult for everyone.
Teacher: Please see the second question on the big screen, Dad bought another Walkman, the original price was 160 yuan, and now it only costs 9% off, so how much is it cheaper than the original price?
Teacher: What is the difference between this question and the previous one?
Teacher: This time, what is asked is not how much money was spent, but how much money it was cheaper. You're so quick to react. Teacher: Then can you help Dad calculate how much the Walkman is cheaper?
Teacher: Please take a group of 4 people**, give everyone 10 minutes, and ask the group representative to share after 10 minutes.
Teacher: Okay, when the time comes, please share with the representatives of Group 2, who had the most intense discussion.
Teacher: What does 1-90% mean?Teacher: It means that it is a few percent cheaper.
Teacher: Well, let's continue to calculate, 160*10%=16 yuan.
Teacher: That is to say, you first calculate the percentage of cheaper, and then how much cheaper it is. Teacher: The result is also 16 yuan.
Teacher: Let's compare the algorithms of the two groups, which one do you prefer?
Teacher: You like the first one, first calculate the current price and then calculate the amount of cheap money. It's easier to understand.
Teacher: You like the second one, which is to calculate the cheap discount first and then the cheap money, so that the calculation is easier. Teacher: Students, through everyone's efforts, we will solve the problem of discountsTeacher: So what is the key to solving the problem of discounts?Teacher: Let's think independently and talk to each other at the same table. Teacher: Please tell the tall girl on the left. Teacher: You think the key is to find the percentage.
Teacher: If we find the percentages, we can convert them into the percentages we have learned and solve the problems. That's right. Teacher: Is there anything else?
Teacher: You think the key is to distinguish the relationship between the original price, the current price and the discount.
Teacher: Well, when solving a problem, it is very important to understand the meaning of the question and distinguish the relationship between quantities.
Teacher: In other words, the discount problem can be regarded as a question of finding what percentage of a number is, and the key is to find the corresponding percentage.
3. Strengthen training and consolidate new knowledge.
Teacher: If you don't practice fake tricks, let's break through the level.
Teacher: Please see the first question and calculate the price of the following items after discounting. Everyone completes it independently, and then proofreads the answers between the tables.
Teacher: Okay, everyone has done it, have you done it right?Teacher: You made a mistake and made a wrong calculation, Teacher: Everyone should be careful, and remember to check it after the calculation.
Fourth, summarize and expand new knowledge.
Teacher: So what have you gained from today's Xi?Teacher: You know the meaning of discounts.
Teacher: You will calculate the discounted price, so that when you go to buy things, you can compare the lower ones more affordably. Teacher: You have gained a lot.
5. Assign homework and internalize new knowledge.
Teacher: At the end of the course, the teacher assigns two assignments to everyone, the first assignment completes Xi 12 questions, the second homework will organize the knowledge learned today into a small math diary, and we will share it together in the next class. Okay, goodbye classmates.
Dear judges, this is the end of my trial lecture, thank you for your patience and listening, can I erase the board book?