The teaching plan of "addition and subtraction" in the first volume of mathematics in the first grade of primary school
Teaching purpose: 1. Ask students to understand the significance of unifying addition and subtraction operations into addition operations.
2. Be able to master the addition and subtraction of rational numbers.
Teaching analysis:
Emphasis: How to unify the mixed operation of addition and subtraction into addition more accurately.
Difficulty: Write a mixed expression of addition and subtraction as the sum of the omitted plus sign.
Teaching process:
First, knowledge orientation:
This section is a comprehensive application of the addition and subtraction of rational numbers, so we must have a deeper understanding of the relevant laws and use them flexibly in the operation.
Second, the new lesson:
1, knowledge base:
First, the law of rational number addition;
Second: the subtraction rule of rational numbers.
Thirdly, the meanings of "+"and "-"in different situations (operation symbols and natural symbols).
2, knowledge formation:
(Reference) Calculation:
According to the law of subtraction, in the order of operation, there are:
Primitive formula
In addition type, the parentheses of each addend and the plus sign in front of it are usually omitted, that is:
This formula is still considered as a summation formula, which can be interpreted in two ways.
Natural symbol: pronounced as "the sum of minus 8, plus 10, minus 6 and minus 4"
According to the meaning of the operation: read "minus 8 plus 10 minus 6 minus 4"
Example: Write by omitting the sum of the plus sign and read (two pronunciations).
Example: Calculate directly according to the operation sequence:
Third, consolidate training:
P46: 1、2
Fourth, knowledge summary:
There are not many new knowledge points involved in this lesson, but special attention is paid to how to ensure that students can minimize the occurrence of mistakes when omitting special symbols, and can accurately read the formula of omitting plus signs.
Verb (short for verb) Homework:
P47: 1、23
Sixth, the daily pre-question:
Teaching plan of addition and subtraction in the first volume of mathematics in the second grade of elementary school
Teaching objective: 1. Understand the mixed problems of addition and subtraction, master the operation order of mixed problems of addition and subtraction, and correctly calculate mixed problems of addition and subtraction.
2. Be able to list the mixed formulas of addition and subtraction according to the pictures.
3. Cultivate students' abilities of observation, comparison and abstract generalization, as well as the ability to solve practical problems by using what they have learned.
4. Cultivate students' good habits of doing problems carefully, calculating correctly and writing neatly.
5. In learning activities, stimulate students' interest in learning and make them realize that there is mathematics everywhere in life.
Teaching focus
Master the operation order of adding and subtracting mixed expressions.
Teaching difficulties
Remember the result of the first operation.
training/teaching aid
Sample diagram, language card, stick.
teaching process
First, stimulate the introduction of interest
Have you read the story of the ugly duckling cartoon? The ugly duckling told about being bullied everywhere because of his ugliness when he was a child. Later, through its tenacious efforts, it finally became a beautiful white swan. Do you know where the beautiful white swan lives? Today, we invited the White Swan to be our guide and take us as a guest.
Second, cooperative exploration.
1, teach swan example 1. Look: How many swans are there in the lake? Demonstration: Three more flies. What about now? Who can tell the whole picture?
[Demonstration: Two more flies. Say the correct picture, and then the teacher demonstrates the complete picture. There are four in the lake, three flew in and two flew in. How many swans are there now? Who can tell the meaning of the picture completely? Do you know how to make it? What should I do if I beg to fly three first? ]
How many swans are there? How to form? (4+3) What if we fly away two more?
Q: How many swans did you fly away? How to express two people flying away?
[After the students answer, the teacher writes "-2" after "4+3". ]
Teacher: What's the difference between the addition and subtraction of this formula we learned before? There is addition and subtraction in this formula, which is a mixture of addition and subtraction. We call it the mixed problem of addition and subtraction (blackboard writing: mixed addition and subtraction).
This formula reads: 4 plus 3, and then subtract 2. (Students read the formula once. )
[How to calculate the mixed questions? Do you know that?/You know what? Do you know that?/You know what? ]
Think about it according to the picture. What is it first?
How do you know 4+3 first and then what? Which number is used to subtract 2? Who can say the meaning of 4+3-2? Show the courseware and encourage students to talk about the calculation process of this problem.
[This question is added at the front and subtracted at the back, so first calculate 4 plus 3 to get 7, and then calculate 7 minus 2 to get 5. ]
2. Teaching Swan Example 2.
Let's look at the swans in another lake.
Demonstration: First four fly away, two fly away, and then three fly in. Students tell pictures and ideas to each other in the group, and then modify them collectively after making independent statements.
[teacher: this formula also has addition and subtraction, which is also a mixed problem of addition and subtraction. What should be counted first? What is the post? Students fill in the boxes in the book and specify the calculation process. ]
3. Summary: Students are really smart. See if there is any difference between what we have learned and what we have learned before.
The two problems just calculated are mixed addition and subtraction problems. Is the L question added or subtracted first? What's first? Question 2: Which comes first, addition or subtraction? What's first?
[Summary: To calculate the mixed problem of addition and subtraction, add first, and if it is subtraction, subtract first. Equations like this are called addition and subtraction. ]
Third, consolidate practice.
(1) Do the "Do" problem on page 67 of the textbook.
[Designate students to say pictures. Index column calculation formula. ]
Q: What is the first question? What is it?
Then the students calculate and fill in the numbers in the box. Modify it when you are finished. ]
(2) Do exercises 15, questions 1.
[Guide the students to look at the pictures carefully, tell the meaning of the questions, fill in the blanks while talking, and correct them collectively. Students say the calculation process. ]
Fourth, classroom exercises.
1, exercise 15, question 2. Instruct students to standardize writing formulas.
2./kloc-Exercise 3 on 0/5. Let the students finish independently and revise collectively.
Verb (abbreviation of verb) summary: How to calculate the mixed operation of addition and subtraction?
Teaching reflection
Teaching plan of "addition and subtraction" in the first volume of mathematics in grade one of three primary schools
Teaching objective: 1. Through teaching, students can correctly calculate the formula of fractional addition and subtraction.
2. In teaching, cultivate students' earnest and careful good study habits.
3. Cultivate students' ability of comparison and observation.
Teaching emphases and difficulties:
Calculation method of fractional addition and subtraction mixed operation; Parenthesized fractional addition and subtraction mixed operation.
Teaching tools:
Small blackboard, slides.
Teaching process:
First, review preparation
1, Teacher: What is the operation order of mixed integer addition and subtraction?
2. Calculate the following questions:
Teacher: Why can scores be added and subtracted at one time and then calculated?
Second, learn new lessons.
Trial example 1.
A simple calculation method is found through modification.
Teacher:
① Is the order of decimal addition and subtraction mixed operation the same as that of integer addition and subtraction mixed operation?
② What's the difference between the example question 1 and the reference question? What is the difference? (discussion)
(3) How to calculate more simply?
Blackboard: It is clear that the mixed operation of fractional addition and subtraction is the same as the mixed operation of integer addition and subtraction. For simplicity, you can divide several fractions at a time and then add and subtract them in turn. Note: For the dotted box, you can think like this when calculating the mixed operation of fraction addition and subtraction, but you can omit this process when doing the problem and write the calculation results directly.
Teacher: What should I pay attention to when calculating the results?
Teacher:
(1) What comes first, then what comes next?
(2) Two steps, one-time or step by step? Students try to calculate and correct. Teacher: ① How to calculate easily?
② Why is it easier to divide by steps?
Note: In the process of drawing a dotted box, you don't need to write it in the future, or write it on draft paper, or you can write the results directly to improve your calculation ability.
Teacher: What should we pay attention to in the result?
Third, consolidate feedback.
1, do it.
2. Judge right or wrong and explain the reasons.
3. List the comprehensive formulas according to the calculation steps in the figure below, and calculate the number.
4. Thinking: Who is taller, Hua or Wang Yingbi? How high is it?