76
Units of area (continued)
Textbook: Part 3, lesson 76, pp. 25–27
GoalMeasure large areas in ares and hectares: 1 a = 100 m², 1 ha = 100 a = 10 000 m².
New words
are (100 m²) · ar (a)hectare · gektar (ha)field · dalaharvest, crop · hosil
Explanation
The area of big pieces of land such as fields, orchards or cotton fields is measured in ares and hectares. 1 are is the area of a square with side 10 m: 1 a = 100 m². 1 hectare is the area of a square with side 100 m: 1 ha = 100 a = 10 000 m². From hectares to m² multiply by 10 000; from m² to ares divide by 100.
Worked examples
3 ha = 300 a = 30 000 m².
3 600 m² = 36 a; 2 ha 7 a = 200 a + 7 a = 207 a.
Class activity
“Field steps”: a 10 m × 10 m area (1 are) is marked out in the schoolyard. Children say how many such areas fit in 1 hectare.
Practice
1
9 ha = ? m²
90000
2
15 a = ? m²
1500
3
8 ha = ? a
800
4
A cotton field is 1 km 500 m long and 400 m wide. What is its area in hectares?
60
5
A farmer sowed wheat on 2 ha 8 a and barley on 1 ha 20 a. On how many ares did he sow in total?
328