Unit 1: Summary of knowledge points of length units: 1, and commonly used length units: meters and centimeters.

2. The measurement unit of shorter objects is usually centimeters, and the measurement unit of longer objects is usually meters.

3. Method of measuring the length of an object: align the left end of the object with the "0" scale of the ruler to see what the scale of the right end of the object is on the ruler. The length of this object is several centimeters.

4. Relationship between meter and centimeter: 1 meter = 100 cm 100 cm = 1 meter.

5. Line segment:

Characteristics of (1) line segment:

① The line segment is straight;

② The line segment has two endpoints;

③ The length of the line segment can be measured.

⑵ Method of drawing line segments: first aim the pen at the' 0' scale of the ruler, point a point on the top, then aim at the centimeter scale of the length to be drawn, point a point on the top, and then connect the two points.

(3) When measuring the length of an object, when the measurement is not started from the "0" scale, the scale number of the starting point should be subtracted from the scale number of the end point.

Knowledge of addition and subtraction of internal numbers in Unit 2 100

Summary of main points:

One, two digits plus two digits

1, two-digit plus two-digit non-carry addition calculation rule: align the same numbers vertically, and then add the numbers on the same numbers.

2, two digits plus two digits carry addition calculation rules:

(1) The same number is aligned; (2) from the unit; (3) exactly ten into ten equals 1.

3. When writing, add two numbers, and the same numbers should be aligned. Starting from single digits, add "1" to the tenth digit for every full digit. Don't leave out "1" when adding the tenth digit.

4. Sum = Appendix+One Appendix = and-Another Appendix

Two digits minus two digits.

1, two-digit subtraction without abdication: the same number is vertically aligned, and then the number on the same number is subtracted.

2. Two-digit minus two-digit abdication minus written calculation rules:

(1) The same number is aligned;

(2) from the unit;

(3) If the number of digits is not enough, extract 1 from the ten digits, add 10 to the number of digits and subtract it.

3. When writing, subtract two numbers from two numbers, and align the same numbers. Starting with single digits, single digits are not enough. Starting from the tenth digit, subtract 1, add 10 to the single digit and then subtract. When calculating ten digits, the backward 1 should be subtracted before calculation.

4. Difference = minus-minus

Negative = negative+difference

Subtraction = minuend-difference

Third, add and subtract and add and subtract.

1, continuous addition and subtraction: the writing order of continuous addition and subtraction is the same as the oral order of continuous addition and subtraction, and they are calculated from left to right.

(1) The addition calculation can be done step by step or vertically. The calculation method is the same as adding two numbers. All the same numbers should be aligned, starting with single digits.

② The continuous subtraction operation can be calculated step by step or written as vertical calculation. The calculation method is the same as subtracting two numbers. The same numbers should be aligned, starting with single digits.

2. Addition and subtraction mixed addition and subtraction mixed formula has the same operation order and vertical writing as addition and subtraction.

3. When writing vertically, you can calculate the mixed operation of addition and subtraction step by step. The method is the same as adding (subtracting) two numbers. The same number of digits should be aligned and counted from single digits. You can also write in a simple way, in a vertical row. First, complete the calculation of the first step, and then add (subtract) the second number with the result of the first step.

Fourth, solve the problem (application problem)

1, step:

1 look at the problem first.

(2) Write the results horizontally, and don't forget to write the unit (the unit is: how much or the words behind).

3 answer.

2. The application problem of seeking more than the number is added; Find an application problem with a number less than one and calculate it by subtraction (note: subtract a large number).

3. On the topic of questioning, you can ask questions like this:

(1) ... and ... a * * * ...

② ... How many (several) more than ...?

(3) How much (several) ... less than ...?

A preliminary understanding of the third unit angle

Summary of knowledge points:

1, angle: red scarf, triangle, clock face, other objects have different angles.

2. Names of parts of an angle: An angle has a vertex and two sides.

3, the characteristics of the angle:

(1) One vertex and two sides (both sides are straight);

② Its two sides are rays, not line segments;

(3) The ray has only one endpoint, so the length cannot be measured.

4. Method of drawing an angle with a ruler: When drawing an angle, first determine a point, and draw two lines in different directions with a ruler to draw an angle.

5. The angle has nothing to do with the length of both sides, but only with the width of both sides.

6. The bigger the sides of the angle, the bigger the angle.

7, draw a right angle method:

Draw a point

Draw a straight line from this point

(3) A right-angled edge of the triangular plate coincides with the drawn straight line, and the right-angled vertex coincides with the drawn point.

④ Draw a straight line along the other right angle of the triangle.

⑤ Mark the right angle symbol after drawing the right angle.

8. To know whether an angle is a right angle, you can compare it with the right angle on a triangle: vertex to vertex, one side to one side, and then look at the other side.

9. Of the three angles on a triangle, 1 is a right angle. Both a square and a rectangle have four corners, which are right angles.

extreme

Unit 4 Intra-table Multiplication (I) and Unit 6 Intra-table Multiplication (II) Summary of Knowledge Points:

1, the meaning of multiplication multiplication is a simple algorithm to find the sum of several identical addends. For example: calculation: 2+2+2=6, calculation by multiplication: 2×3=6 or 3×2=6.

2. Writing and reading multiplication formula.

(1) The method of rewriting the formula of continuous addition into the formula of multiplication: To find the sum of several identical addends, multiplication can be used. When writing a multiplication formula, you can write the same addend first, then the multiplication symbol, then the number of the same addend, and finally the equal sign and the addition. You can also write the number of the same addend first, then write the multiplication symbol, then write the same addend, and finally write the sum of equal sign and continuous addition. For example, if 4+4+4= 12 is rewritten as a multiplication formula, it is 4×3= 12 or 3× 4 =12. When reading multiplication formulas, read them in the formula order. For example, 6×3= 18 is read as "6 times 3 equals 18".

3. The names and practical significance of each part in the multiplication formula. In the multiplication formula, the number before multiplication and the number after multiplication are called "multipliers"; The number after the equal sign is called the product.

4, the meaning of multiplication formula:

It is relatively simple to find the sum of several identical addends by multiplication. The multiplication formula represents the sum of several identical addends. For example, 4×5 means five 4+ s or four 5+ s..

When addition is written as multiplication, the sum of addition is equal to the product of multiplication.

6. In the multiplication formula, two multipliers exchange positions and the product remains unchanged.

7. Names and calculation formulas of each part of the formula.

(1) Multiplication: Multiplier× Multiplier = Product

(2) Addition: Appendix+Appendix = sum.

Sum-Appendix = Appendix

(3) subtraction: minuend-subtraction = difference

Subtraction = difference+subtraction

Subtraction = minuend-difference

8. In the multiplication formula of 9, 9 multiplied by 9 or 9 multiplied by several can be regarded as tens minus several, where "several" refers to the same number. For example:1× 9 =10-19× 5 = 50-5.

9. Look at the picture and write the multiplication, addition and subtraction formulas:

(1) Multiplication and addition: the same part is represented by multiplication first, and then the different parts are added.

(2) Multiplication and division method: first calculate each copy as the same, write multiplication, and then subtract the redundant part.

(3) When calculating, multiply first, then add and subtract.

Addition: 3+3+3+2 = 14.

Multiplication and addition: 3×4+2= 14

Multiplication and subtraction: 3×5- 1= 14

10, "How many times is a number" is calculated by multiplication. Use: this number times multiple or multiple times this number.

1 1, there are several identical addends, which are several times the same addend. For example, three fives is three times as much as five.

Unit 5 Observing Objects

Summary of knowledge points:

1. You should know that the shapes of objects observed from different positions may be different.

2. Identify the shapes of simple objects seen from different positions.

3. Identify the shapes of simple geometry seen from different positions.

4. Solve simple problems by reasoning.

Unit 7 Knowing Time

Summary of knowledge points:

1, in the specific life situation, with the help of the clock face to understand the time unit "minute", we know that 1 is equal to 60 minutes.

2. Combined with intuitive demonstration and operation, we know that it takes 1 minute for the minute hand to walk a "small grid", 5 minutes for the minute hand to walk a "big grid" and 60 minutes for the minute hand to walk a circle.

3. Have a preliminary understanding of when you can read and write (5 minutes and 5 minutes).

4, will use the knowledge of time to solve some simple practical problems.