Keywords: Cuboid Cuboid Primary School Grade Four
This article applies to: the fourth grade of primary school.
Composition source:
This 350-word composition is about the fourth grade of primary school. The topic is: Mathematical Manuscript-Understanding of Cuboid and Cube. Everyone is welcome to contribute enthusiastically.
Mathematical Manuscripts —— Understanding of Cuboid and Cube
Plate 1: Understanding Cubes and Cubes
When you look at a cuboid from one direction, you can see at most three faces at the same time. A cuboid has six faces, two opposite faces are exactly the same, all six faces are rectangles (sometimes two opposite faces are squares), and the edge where two faces intersect is called an edge. A cuboid has 12 sides, and the side lengths can be divided into three groups, and the four opposite sides are equal in length. The point where three sides intersect is called a vertex, and a cuboid has eight vertices. The length of three sides intersecting at a vertex is called the length, width and height of a cuboid. A cube is a three-dimensional figure composed of six identical squares. Cubes are also called cubes. A cube has all the characteristics of a cuboid. It can be considered as a cuboid with equal length, width and height, which is both a cube and a special cuboid.
A cuboid has six faces, the opposite faces are exactly the same; A cuboid has 12 sides, and the sides are equal in length; A cuboid has eight vertices, a cube has six identical faces, all 12 sides of the cube have the same length, and the cube has eight vertices.
Panel 2: Surface areas of cuboids and cubes
The total area of six faces of a cuboid or cube is called its surface area.
The areas of upper and lower surfaces (length× width), front and rear surfaces (length× height) and left and right surfaces (width× height); The surface area of a cuboid = length× width× 2+length× height× 2+width× height× 2 = (length× width+length× height+width× height) × 2; Surface area of cube = side length × side length ×6.
Plate 3: Volume and unit of volume
The water level in the sink has risen because stones occupy some space. Because the wood blocks occupy some space, there is extra sand. The space occupied by an object is called its volume. Unit of volume is used to measure volume. Commonly used unit of volume includes cubic centimeter, cubic decimeter and cubic meter, which can be written as cm2, dm3 and m3 respectively. The volume of a cube with a side length of 1 cm is 1 cm 3. The volume of a fingertip is about 1 cm3, and the volume of a peanut is about 1 cm3; The volume of a cube with a side length of 1 decimeter is 1 cubic decimeter. The volume of the chalk box is 1 cubic decimeter; A cube with a length of 1m has a volume of 1 m3, and the volume of a 29-inch TV set in a carton is about 1 m3. Measuring the volume of an object depends on how much unit of volume it contains. 1 cubic decimeter = 1000 cubic centimeter; 1 m3 = 1000 cubic decimeter; 1 m3 = 1000000 cubic centimeters.
Plate 4: Volume and unit of volume
The volume of objects that a container can hold is called their volume. Unit of volume is generally used to measure volume, but the volume of liquids, such as water and oil, is usually measured in liters and milliliters, and can also be written as L and mL.
1 l = 1 cubic decimeter
1 ml = 1 cm3
1 l = 1000 cubic centimeter
Panel 5: Calculation of cuboid and cube volumes
The unit of volume number contained in a cuboid is the volume of the cuboid. The volume of a cuboid is equal to the product of length, width and height.
Volume of cuboid = length× width× height V=abh
Volume of cube = side length × side length × side length V=aaa
The area at the bottom of cuboids and cubes is called their bottom area.
Volume of cuboid or cube = bottom area × height V=sh
The volume (http://Zw.lIuXueE86.Com) of a cuboid and a cube is calculated in the same way. But the length, width and height are measured from the inside of the container.
Section 6: Happy Review
Cubes are special cuboids. Their relationship is a cube = a special cuboid.
A cuboid and a cube have six faces, and the opposite faces are exactly the same. To calculate their volume, you can multiply the bottom area by the height. V=SH
Realistic problem: How to find the volume of beverage box? Mathematical problem: How to find the volume of a cuboid? Lenovo has knowledge and experience: the size of a volume is the number contained in a unit volume. Find a way: cut everything, put it away, count it, and calculate it. Conclusion: Guess, verify and summarize the volume formula: V=abh. Solve the problem: explain the application, and use the formula to find the volume of a cuboid to solve the problem of finding the volume of a beverage box.