The position of the first unit is opposite to the direction 1, ① (east and west), (south and north), (southeast-northwest) and (southwest-northeast). (2) know who is the standard to judge the position. ③ Understanding position is relative, not absolute.

2. Maps are usually drawn by (upper north, lower south, left west and right east). Mark the east, west, north and south first when you do the problem. )

I can read the simple road map and describe the walking route. Be sure to write clearly where to go, how many meters you have walked, and where to go again. The same place can be described in different ways. The same place has different walking routes. Usually find a shorter route.

The compass is used to indicate the direction. One hand always points to the south and the other hand always points to the north.

5. Orientation knowledge in life: ① Polaris is always in the north. The shadow is opposite to the direction of the sun. The sun is in the east in the morning, in the south at noon and in the west at night. (4) The wind direction is opposite to the direction in which the object inclines.

The divisor of the second unit is the division of a single digit.

1, pay attention when calculating orally: (1)0 divided by any number (except 0) equals 0; (2) Multiply 0 by any number to get 0; (3)0 plus any number will get any number itself; (4) Minus 0 from any number to get any number itself.

2. Division without residue: dividend/divisor = quotient, quotient× divisor = dividend, dividend/quotient = divisor.

Division with remainder: dividend/divisor = quotient ... remainder, quotient× divisor+remainder = dividend, (dividend-remainder)/quotient = divisor.

3. Stroke division sequence: determine the number of digits of quotient, try quotient, check, check.

4. Basic Law: (1) Divide from the high position, and write the quotient at that position; (2) When three digits are divided by one digit, the quotient is three digits. If the percentile is not enough, the quotient is two digits; (If there are not enough points, just look at two businessmen. (3) Which bit has a remainder, it is merged with the number on the next bit and then divided; (4) If the quotient of 1 is not enough, add 0 to occupy a place; The remainder of each division must be less than the divisor.

5. Extracurricular knowledge expansion: the characteristics of multiples of 2, 3 and 5. Multiply of 2: Numbers in units of 2, 4, 6, 8 and 0 are multiples of 2. Multiply of 5: A number with a bit of 0 or 5 is a multiple of 5. Multiply of 3: The sum of the numbers on each digit is a multiple of 3, and this number is a multiple of 3.

6. On multiples: the sum of two numbers and multiples = 1 multiple, and the difference between two numbers = 1 multiple.

7. Sum and difference problem (sum of two numbers-difference of two numbers) ÷2= smaller number, (sum of two numbers+difference of two numbers) ÷2= larger number.

extreme

Unit 3 Composite Statistics Table 1. Combine two or more related simple statistical tables into one statistical table, which is a composite statistical table.

2. To observe and analyze the double-entry statistical table, we should first look at the header to find out all the contents, and then analyze and answer questions according to the data.

Unit 4 Multiply two digits by two digits

Oral multiplication

1, the oral calculation method of multiplying two digits by one digit: (1) Divide two digits into integer ten digits and one digit, multiply the integer ten digits and one digit by one digit respectively, and finally add the products of the two multiplications. (2) calculate vertically in your mind.

2. Oral calculation method of multiplying a whole hundred by a number: (1) First multiply a number by an integer, then multiply a number by an integer, and finally add the products of the two multiplications. (2) Multiply a number by the first two digits of an integer, and then add a 0 at the end of the product. (3) Column vertical calculation in the brain.

3. Oral method of multiplying a number by 10: Multiplying a number by 10 means adding a 0 at the end of this number.

4. the oral calculation method of multiplying two digits by integer ten: multiply the two digits with the number on integer ten first, and then add an o at the end of the product.

Pencil multiplication

1. Multiply the first factor by the number of digits of the second factor, then multiply the number of digits of the second factor (the product is aligned with the number of digits), and finally add the two products.

2. Any question "Is it enough, can it?" There are three steps: ① calculation, ② comparison and ③ answer. → Don't forget to compare this step.

3. Correlation formula: factor × factor = product, product ÷ factor = another factor.

4. The product of two digits multiplied by two digits may be (3) digits or (4) digits.