How to explain the simple calculation of 3rd grade math scores clearly and understandably?

If the denominator is the same, only the numerator is added or subtracted, and the denominator is different, so the same denominator is divided first, and then the numerator is added or subtracted. The numerators are multiplied, the cross is divided first, and then the denominator is multiplied by the denominator, and the numerator is multiplied by the numerator. The fractions are divided, multiplied, and multiplied.

You need to write out different topics first, one type at a time, and then let the child do more exercises.

Two laws: the legal law of fraction addition and subtraction: 1. Addition and subtraction with the denominator, only the numerator is added and subtracted, and the denominator remains unchanged; 2. If the denominator is not the same, first divide the denominator with the same denominator, and then add or subtract it.

Just let the students understand that the addition and subtraction of fractions is the same as the addition and subtraction of integers. The difference is that the denominator is the same, only the numerator is added or subtracted, and the denominator remains the same. In the third grade, there is no general credit, so there is only this one rule.

First, let the students calculate through the graph and express it with the formula, through comparison, observation, and induction, the denominator does not change, and the numerator is added or subtracted.

The denominator doesn't move, just add up the two numerators.

First, let students pay attention to whether it is the same denominator or different denominator, the same denominator is directly added and subtracted, and the different denominator is divided.

The illustration is easy for students to understand. For example, draw a line diagram or a circle, and then divide them into several equal parts, and take a few of them to be fractions.

The calculation of third-grade scores is too simple, and the children also have a certain ability to learn on their own, so it is okay for the children to learn on their own.

The denominator remains unchanged, and the numerators are added and subtracted.

Let's talk about it first and then let the child do more, so that the child can really understand.

Divide apples Then a piece is a fraction, and add together a fraction.

According to the number of solutions to the problem, prepare a bunch of small teaching sticks and explain according to the topic.

Preview first, then listen to the class, then review, and do more questions.

It is best to show it in real objects and let the students feel it for themselves.

Combined with the example of the real thing.

It may be a little easier to accept the use of illustrations.

Simple calculations of third-grade fractions and other integersEasy to calculateThe method is the same, there are a total of 5 calculation methods, which are as follows:

The first type: the multiplicative distributive law.

The most common method used in simple calculations is the multiplicative distributive property. The multiplicative distributive property refers to ax(b+c) = axb+axc, where a, b, c are arbitrary real numbers.

The second type: the associative law of multiplication.

The associative law of multiplication is also a method of doing simple operations, which is expressed by letters as (a b) c=a (b c), and its definition (method) is: multiply three numbers, multiply the first two numbers, and then multiply the third number.

The third type: the commutative law of multiplication.

The commutative property of multiplication is used to swap the digits of each number: a b = b a.

Fourth: the commutative law of addition.

The commutative property of addition is used to invert the positions of individual numbers: a+b=b+a.

Fifth: the associative law of addition.

The associative law of addition combines regular terms to calculate: (a+b)+c=a+(b+c).

Examples:

3) Digging with belts.

4) Stupid Mountain.

1. The meaning of fractions: divide a whole into several parts, take out a few parts, and divide these parts by the total number of parts is a fraction of the whole, writing: 4 5

It is to divide the whole into 5 equal parts and take out 4 of them.

2. Fraction: It is the ratio of one part of the whole to the whole after dividing the whole into several parts.

Fractions: The meaning of the same fraction, the "several" in front indicates the total number of parts divided as a whole, and the "several" in the back indicates the number of copies taken out.

3. The more parts of a whole are divided equally, the smaller the number of each part of it represents, which involves a concept, the unit "1", that is, the whole is regarded as one.

4. How to compare the size of the scores:

The numerator is the same, the denominator is smaller, and the denominator is smaller. It is understood that the smaller the number of parts of a whole, the greater the amount of each part is expressed.

The denominator is the same, the large numerator is large, and the small numerator is small. It is understood that if a whole is divided into the same number of parts, the smaller the number of parts taken out, the smaller the amount represented.

5. Addition and subtraction of fractions:

Calculation method of addition and subtraction of fractions with the same denominator: addition and subtraction of fractions with the same denominator, the denominator remains unchanged, and the numerator is added and subtracted.

How to calculate the number of 1 minus a fraction: When calculating 1 minus a fraction, first write 1 as the same fraction as the denominator of the subtraction, and then calculate.

General fraction addition and subtraction: first through the score, then add and subtract, the general fraction is to turn the denominator into the least common multiple of the two denominators.

6. Find a fraction of a number that is another number: just divide this number by another number;

7. Find out what is the fraction of a number: multiply this number by the fraction;

8. Know what the fraction of a number is, find the number: divide the number by the fraction.

The fraction of the same denominator is added and subtracted, the numerator of the denominator is unchanged and subtracted as the numerator, and the different denominator is the same first.

1. Review old knowledge and highlight the unit of fraction 1Students look at a diagram to describe the fraction and use a graph to communicate the relationship between the two fractions: 4 in 46 Invite students to name several fractions with the same denominator and imagine the graph representing the fraction.

Teaching Objectives: 1. To enable students to experience the process of abstracting quantitative relations from real-life situations, master the quantitative relations of problems that require two-step operations, and how many fractions of a number are in a row, as well as problem-solving ideas and methods, and develop students' ability to think creatively.

2. Improve students' ability to discover, analyze and solve problems, organize students to practice and be independent, and cultivate students' ability to analyze, compare and abstract. Cultivate in students the spirit of cooperative exploration.

Teaching is a major and difficult task.

Teaching focus: 1. To enable students to master the quantitative relationship of the problem that needs to be operated in two steps, to find the fraction of a number, as well as the problem solving ideas and methods, and to develop students' innovative thinking ability.

2. Let students understand that the quantity of the unit "1" is different in two comparisons, and master the quantitative relationship of the problem of finding the fraction of a number in a row that requires two-step operation, as well as the problem solving ideas and methods.

Teaching difficulty: Correctly understand and solve the problem of finding the fraction of a number in a row.

Teaching tools. Courseware.

Teaching process. Pre-class talk: Students are really spirited, let's compete in this class to see who is the best!

1. Review and introduce to awaken old knowledge.

1.Indicate which quantity in each of the following groups is the quantity of the unit "1":

2. Create a situation and learn more.

1. Do students like to eat vegetables? Then let's go to the farmer's uncle's greenhouse and take a look. )

1) Read the scene silently.

2) Who can read it out loud.

2. What mathematical information did you collect? (Half of them are planted with various turnips,) who can say what they understand about this sentence.

3. Based on this mathematical information, who can ask a mathematical problem?

4. Introduce board book topics. This is the question of how many fractions of a number we have to find in succession in this lesson.

5. How do you plan to use to represent the mathematical information and problems in the problem?

6. Hands-on operation. Choose your preferred method and get started.

7. Try to solve the problem yourself.

8. After doing it, think about it and then communicate in the group: (1) What method did you choose to solve the problem and destroy the child?

2. What to count first? What's the recount? In whose unit is the quantity of "1"?

9. Class debriefing: Who will tell me what you think?

3. Autonomy and critical communication.

Analysis & Answer Sharing:

5. Summarize the whole lesson to enhance understanding.

What did you learn from this lesson?

6. Assign homework. Exercise 3: 16 pages.