Teaching requirements:
1. Make students know the meanings of unit price, quantity and total price, speed, time and distance, and understand and master these two groups of quantitative relations.
2. Initially cultivate students' ability to use mathematical terms, as well as comprehensive, abstract, generalization and other thinking abilities, and penetrate the point of view that things are interrelated.
Teaching process:
First, review the old knowledge.
1. Oral response.
(1)1How much is a pencil box and five pencil boxes in 0 yuan?
(2) How many pencil boxes can I buy per 10 yuan in 50 yuan?
(3) 50 yuan bought five identical pencil cases. How much is each?
The students call the roll and the teacher writes it on the blackboard.
2. Student formation.
(1) How many kilometers is a car going at 50 kilometers per hour in three hours?
(2) A car travels150km, with a speed of 50km/h.. How many hours did it travel?
(3) A car travels for 3 hours 150km, and how many kilometers does it travel per hour on average?
Students list the formulas in their exercise books, and then answer and proofread them orally.
Second, the new curriculum teaching
1. Introduce new courses.
We have learned many practical problems, know that there are various quantitative relations in industrial and agricultural production and daily life, and have been exposed to many quantitative relations. What are the quantities in the above questions and what is the relationship between them? Today we are going to learn some common quantitative relations (blackboard writing topics).
2. Teaching examples 1.
(1) Give an example of 1. Students' reading problems.
Ask the students to list the answers in the textbook.
Students answer the formula and get the numbers. The teacher writes them on the blackboard.
(2) The meaning of teaching unit price, quantity and total price.
Question: What are these two questions about?
What are the characteristics of the conditions of these two questions? What kind of questions are they asking?
Note: These two questions are both about the price of the purchased goods. Here, each pencil costs 20 cents and each volleyball costs 55 yuan. The price of every commodity is the unit price. (Blackboard: unit price) The number of pieces bought in this way is the quantity. (Blackboard: Quantity) The money used is the total price (blackboard: total price).
Question: What is the unit price of your math book? Do you know the unit price of your pencil case?
Please tell us the following unit price, quantity and total price.
The school bought 20 sets of school uniforms, each in 600 yuan and 30 yuan.
(3) Summarize the quantitative relationship among unit price, quantity and total price.
Who can tell us the unit price and quantity of the pencils in question (1), and what did you get? How do you ask? What is the unit price and quantity in question (2)? Begging for what? How do you ask? What are the characteristics of these two questions in calculation methods?
From the above two questions, what kind of quantitative relationship do you find between unit price, quantity and total price (blackboard writing: unit price quantity = total price)?
[Comment: Let students observe different quantities and think about what quantity they want and how to get it, which can not only consolidate the concept of quantity just learned, but also analyze the calculation methods of these two questions. Then guide to find the same characteristics of * * * and summarize the quantitative relationship, which is to inspire students to synthesize, abstract and summarize on the basis of analysis. This kind of teaching can make students know the abstract quantitative relationship on the basis of perceiving and analyzing specific problems, which is not only conducive to students' understanding, but also conducive to cultivating their initial logical thinking ability. 〕
Question: Please think about this relationship. If you know the total price and unit price, what else can you ask for? How to find it (blackboard: total price, unit price = quantity)?
Follow-up: Why should the total price be divided by the unit price?
Question: think again, if you know the total price and quantity, what else can you ask for? How to ask? How did you come up with it (blackboard writing: total price quantity = unit price)?
(4) Now look at a set of three quantitative relations here, which are closely related. Do you think you can remember the other two by remembering one? According to what knowledge do you remember the other two?
Summary: From the three quantitative relationships here, we can see that according to the relationship between unit price, quantity and total price, as long as we know these two quantities, we can find the third quantity. When we remember this set of quantitative relations, as long as we remember that unit price quantity = total price, we can draw the conclusion that total price unit price = quantity and total price quantity = unit price according to the relationship between the parts of the multiplication formula.
3. Organize exercises.
(1) Do some exercises. Question 1.
Reading problems. Question: What is the quantitative relationship of example 1?
Name the students and give oral examples to illustrate the problem of finding the total price.
Question: Who can give an example of measuring quantity? How about the unit price?
(2) Practice the second question.
Name three people performing on the blackboard, and the rest of the students performing on the textbooks.
Collective revision.
Q: What quantitative relationships are applied here? Of the three quantities, unit price, quantity and total price, how many quantities do you need to know to ask a quantity?
It is pointed out that if we know two of the unit price, quantity and total price, we can find the third quantity.
4. Teaching example 2.
(1) Example 2, students look at the questions.
Ask the students to list the answers in the textbook.
Students answer the formula and get the numbers. The teacher writes them on the blackboard.
(2) Question: What are these two questions about, that is, the trip problem, in which the distance traveled per unit time is 45 kilometers per hour, 70 meters per minute is the speed, and two hours and six minutes (blackboard writing: speed) is the walking time, and 90 kilometers and 420 meters (blackboard writing: time) are calculated. (blackboard writing: distance)
(3) Question: What is the speed of the car in question (1)? What about walking time? What is the result? How do you ask?
Question (2) What is the walking speed and time of Xiaodong? What is this? How do you ask?
What are the characteristics of these two questions in calculation methods?
From these two questions, what is the relationship between speed, time and distance (blackboard: speed and time = distance)?
Question: If you know the distance and speed, what can you ask for? How to ask the time? How did you come up with it (blackboard: distance speed = time)?
According to the quantitative relationship, what two conditions are needed to find the speed? How to ask? Why do you ask for this (blackboard writing: travel time = speed)?
(4) Which one do you mainly remember here, so that you can remember the other two? What knowledge can you think of the other two from the multiplication relation?
Please read these three quantitative relationships together.
Summary: Speed, time and distance are closely related quantities. As long as we know two of them, we can find the third quantity. When memorizing this set of quantitative relations, as long as you remember that speed time = distance, you can calculate distance speed = time and distance time = speed according to the multiplication and division relationship.
5. Organize exercises.
(1) What is the quantitative relationship between the following conditions?
① The ship travels for 5 hours 125km.
② The train speed from Nanjing to Shanghai is 6 1 km, * * * 305 km.
(3) Xiaohua has to walk 800 meters from home to school, and Xiaohua has to walk 16 minutes, walking 50 meters per minute.
(2) Do an exercise on the third question.
Reading problems. Ask the students to illustrate the problem of finding the distance with examples.
Which student has a problem to find time? Can you give an example of speed?
(3) Do some exercises of Question 4.
Name the students and tell the relationship between the numbers.
Name three people performing on the blackboard, and the rest of the students performing in the exercise books.
Collective revision.
Question: How to find the distance? How to find time? What about speed?
Third, the class summary
What two groups of common quantitative relations are studied in this course? Can you elaborate on the quantitative relationship between the two groups? Can we think about the remaining quantitative relations by remembering which two?
Fourth, homework
Class assignments: exercise 12, question 1 and 2.