Unit of area measurement: Square centimeter
1.1. Knowledge to remember
- To measure area we use area units, for example:
square centimeter.
- A square centimeter is the area of a square with sides 1cm long. Square centimeter is abbreviated as cm^{2}.
1.2. Solving Textbook Exercises
Lesson 1: Write according to the pattern
Read | Write |
Five square centimeters | 5cm^{2} |
One hundred and twenty square centimeters | |
1500 cm^{2} | |
Ten thousand centimeters |
Solution guide:
- Read the number then read the unit of measure
- Square centimeter is abbreviated as cm^{2}
Read | Write |
Five square centimeters | 5cm2 |
One hundred and twenty square centimeters | 120cm^{2} |
One thousand five hundred centimeters | 1500 cm2 |
Ten thousand centimeters | 10000cm^{2} |
Lesson 2:
a) Write in the dot (according to the form)
Figure B consists of… squares of 1cm^{2}
The area of figure B is equal to…
b) Compare the area of figure A and the area of figure B.
Solution guide:
- Count the number of squares in figure B.
- The area of figure B is equal to the number of squares just counted.
- Compare the area of figure A with the area of figure B.
a) Figure B consists of 6 squares of 1cm^{2}
Area of figure B is 6cm^{2}
b) The area of figure A is equal to the area of figure B.
Lesson 3: Calculate by sample
Model: 3cm^{2} + 5cm^{2} = 8cm^{2 } 3cm^{2} x 2 = 6cm^{2}
a) 18cm^{2} + 26cm^{2} = b) 6cm^{2} x 4cm^{2} =
40cm^{2} – 17cm^{2} = 32cm^{2} : 4cm^{2} =
Solution guide:
Perform calculations with numbers and then add centimeters after the result.
a) 18cm^{2} + 26cm^{2} = 44cm^{2} b) 6cm^{2} x 4cm^{2} = 24cm^{2}
40cm^{2} – 17cm^{2} = 23cm^{2} 32cm^{2} : 4cm^{2 }= 8cm^{2}
Lesson 4: Blue sheet of paper has an area of 300cm^{2}, the red paper has an area of 280cm^{2}. How many square centimeters is the area of the blue sheet of paper larger than the area of the red paper?
Solution guide:
Summary:
To find the solution, we subtract the area of the red paper from the area of the blue paper.
Solution
The area of the blue sheet of paper is larger than the area of the red paper in square centimeters:
300 – 280 = 20 (cm^{2})
Answer: 20 cm^{2} .
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