1, the meaning of multiplying a meaningful fraction by an integer: a simple operation to find the sum of several identical fractions.
The meaning of multiplying the score by the score: what is the score of this score?
2. Calculation method: molecules are multiplied, and the product of multiplication is made into molecules; The denominator is multiplied, and the product is used as the denominator, and the result becomes the simplest fraction.
Unit 3 Fractional Division
1, reciprocal: If the product of two numbers is 1, then one number is the reciprocal of the other. (0 has no reciprocal, and the reciprocal of 1 is itself)
2. The calculation method of dividing a number by a fraction: dividing a number (except 0) is equal to multiplying the reciprocal of this number.
3. Know the fraction of a number and find the solution of the application problem of this number. ★ Students should be encouraged to solve with equations.
Unit 5 Fractional Mixing Operation
1, the order of decimal mixing operation is the same as that of integer mixing operation.
2. The law of integer operation is also applicable to decimal operation.
3. Application of fractional mixed operation: solving some practical problems with equations.
★ When solving problems like "Fractional Mixed Operation (Ⅲ)", students are required to solve equations.
Unit 6 percentage
1, meaning of percentage: A number indicating that one number is a percentage of another number is called a percentage. Percentage is also called percentage or percentage.
2. Be able to read and write correctly.
3, can correctly carry out decimal, fractional and percentage operations.
Decimal percentage: move the decimal point two places to the right, followed by a percent sign.
Fraction becomes percentage: first decimal, then percentage.
Percentilized fraction: Write a fraction with denominator of 100 first, and then convert it into the simplest fraction.
Decimal percentage: first remove the percent sign and move the decimal point to the left by two places.
4. Application of percentage. ★ Solve the problem of "How many percent of a number is known, and find this number" with equations.
Space and geometry
The second unit cuboid (1)
Features: A cuboid has 8 vertices, 6 faces and 12 sides; The edges are divided into 3 groups, each group is equal in length; The areas of the opposite faces are equal.
A cube has 8 vertices, 6 faces and 12 sides; All sides are equal in length; The areas of the six faces are all equal.
Side length: cuboid side length = (length+width+height) ×4.
Cube side length = side length × 12
Surface area: cuboid surface area = (length× width+width× height+length× height) ×2.
Surface area of cube = side length × side length ×6
The fourth unit cuboid (2)
Units (multiplication of large units and division of small units)
Unit of volume: m 3 1000 decimeter 3 1000 cm 3 (the propulsion rate between adjacent unit of volume is 1000).
Unit of volume: 1000ml.
Volume cuboid volume = length× width× height
Cubic volume = side length × side length × side length
Length and cube volume = bottom area × height
Volume measurement of irregular objects;
Option 1: The volume of the stone = the volume of the rising part.
Option 2: the volume of the stone = the volume of the overflow part.
Statistics and probability
Unit 7 Statistics
Features of various statistical charts: Bar charts are easy to see the amount of data.
It is easy to see the changing trend of data in broken-line statistical chart.
The fan-shaped statistical chart can clearly see the relationship between the whole and the part.
Median and mode
Median: arrange a set of data from small to large (or from large to small), and the middle number is the median of this set of data. When the number of a set of data is even, the median takes the average of the middle two numbers.
Mode: The number with the highest frequency in a set of data is called the mode of this set of data.
Comprehensive practice
Mathematics and life: painting walls
Mathematics and Life: Folding
Math and Shopping: Estimating Costs
Mathematics and Shopping: Shopping Strategies
Mathematics and Shopping: Packaging Knowledge