I. Measurement of quantity

1. Length units are: kilometers, meters, decimeters, centimeters and millimeters. Write down the forward speed between them.

The units of area are: square kilometers, hectares, square meters, square decimeters and square centimeters. Note the progress between them.

Volume units are: cubic meter, cubic decimeter (liter) and cubic centimeter (milliliter). Write down the forward speed between them.

The units of mass are tons, kilograms and grams. Note the progress between them.

Time units are: century, year, month, day, hour, minute and second. Write down the progress between them.

2. The big months of the year are: 1, 3, 5, 7, 8,/kloc-0, 65438+February, ***7, and 3 1 day per month.

There are: April, June, September, 165438+ 10, ***4, 30 days per month.

February in a normal year has 28 days and leap year has 29 days.

The method of recording the moon with your left hand

There are four quarters in a year and three months in each quarter.

4. Leap year in normal years: a leap year is usually a multiple of 4 in the Gregorian calendar year, which is a whole hundred, and it must be a multiple of 400 to be considered a leap year.

5. Nominal number: the measured number and the unit name are collectively called nominal number.

Single number: a single number with only one company name is called a single number.

Composite number: A compound number is one with two or more unit names.

6. Name rewriting: the multiplication rate of the high-grade unit name converted into the low-grade unit name, and the low-grade unit name converted into the high-grade unit name divided by the multiplication rate.

2. Preliminary knowledge of geometry

1. The connection and difference between line segment, ray and straight line: the connection is that all three are straight lines, but the difference is that the line segment has two endpoints and its length can be measured; Ray has only one endpoint and can extend indefinitely; A straight line has no end points, and both ends can extend indefinitely. Rays and straight lines are infinitely long.

2. Angle: A figure composed of two rays drawn from a point is called an angle.

3. The size of the angle: The size of the angle depends on the size of both sides. The bigger the fork, the bigger the angle.

1. The unit of measuring angle: degree, which is expressed by symbol.

2. An angle less than 90 is called an acute angle; An angle greater than 90 and less than180 is called an obtuse angle. The angle between two sides in a straight line is called a right angle. Boxer 180.

3. Vertical line: When two lines intersect at right angles, they are perpendicular to each other, and one of them is the vertical line of the other. The intersection of these two straight lines is called vertical foot. (Description of drawings)

4. Parallel lines: Two straight lines that do not intersect on the same plane are called parallel lines. It can also be said that these two straight lines are parallel to each other.

(Illustration) The vertical line segments between parallel lines are all equal in length.

5. Triangle: A figure surrounded by three line segments is called a triangle.

6. The classification of triangle:

(1) By angle: acute triangle, obtuse triangle, right triangle.

(2) Divided by sides: general triangle, isosceles triangle and equilateral triangle.

10. The sum of the three internal angles of a triangle is 180.

Quadrilateral: a figure surrounded by four line segments.

12. The circle is a curve figure. The distance from any point on the circle to the center of the circle is equal, and this distance is the length of the radius of the circle.

13. There are countless circles in radius and diameter. The diameter of the same circle is twice the radius, and the radius is half the diameter.

14. Axisymmetric graph: If a graph is folded in half along a straight line, two graphs of the straight line can completely overlap, and this graph is an axisymmetric graph. The straight line where the crease lies is called the symmetry axis.

15. Axisymmetric figures in the learned figures include: circle, isosceles triangle, equilateral triangle, rectangle, square and isosceles trapezoid.

16. Perimeter: The sum of all the side lengths surrounding a graph is the circumference of the graph.

Area: The size of an object's surface or closed plane figure is called their area.

17。 Surface area: The sum of all the areas of a three-dimensional figure is called the surface area of this three-dimensional figure.

Volume: The size of the space occupied by an object is called the volume of the object.

18. Both cuboids and cubes have 12 sides, 6 faces and 8 vertices.

A cube is a special cuboid and an equilateral triangle is a special isosceles triangle.

19. Three characteristics of the cylinder: (1) The thickness of the top and bottom is the same; (2) The side is curved; (3) The two bottom surfaces are the same circle.

20. Height of cylinder: The distance between two bottom surfaces of cylinder is called the height of cylinder. A cylinder has countless heights, all of which are parallel and equal.

2 1. Expand the side of the cylinder to get a rectangle. The length of this rectangle is equal to the circumference of the bottom of the cylinder, and the width is equal to the height of the cylinder.

22. Pi is an infinite cyclic decimal. =3. 14 1592653

23. Divide the circle into several parts, and the figure is close to a rectangle. The length of this rectangle is half of the circumference, and the width is the radius of the circle.

24. Height of the cone: The distance from the apex of the cone to the center of the bottom surface is the height of the cone.

25. The volume of a cone with equal bottom and equal height is cylindrical, and the volume of a cylinder with equal bottom and equal height is three times that of a cone.

For cylinders and cones with equal volume and bottom area, the height of the cylinder is conical and the height of the cone is three times that of the cylinder.

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