Recognise Right Angles
Recognise Right Angles
Unit :
2S2 Angles (I)
Topic :
Recognise Right Angles
Key Stage :
1
Learning Objectives:
1.
Recognise right angles through rotation of an object
2.
Understand the meaning of right angles
3.
Describe the size of an angle by using ‘bigger than/ smaller than/ equal to a right angle’
Prerequisite Knowledge:
Understand the meaning of an angle
1.
The teacher asks pupils to face an object (e.g. the blackboard) in the classroom, and turn around until they face the same object again. Pupils then say that they have made one complete turn.
2.
The teacher asks pupils to face an object and make a half turn. Pupils explain how they know they have made a half turn.
Questions for Discussion:
1.
How do you know you have made a complete turn?
2.
How do you know you have made a half turn (for example, facing a different wall when stops turning or how much his/ her body has turned)?
1.
The teacher asks pupils to turn half of a half turn, and introduces to pupils that a right angle is half of a half turn. Then, the teacher asks pupils to face different objects and try to make a turn of a right angle.
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Recognise Right Angles
2.
The teacher demonstrates the size of a right angle by rotating objects (e.g. geometry-strips or rulers) (as shown in the following figure).
3.
Pupils make turn of a right angle with different objects (e.g. a pencil, a pencil case or a ruler).
Question for Discussion:
Are there any objects in the classroom with a right angle?
1.
The teacher sets a specified time on a clock face. The time shown is in the unit of hour (e.g. two o’clock, three o’clock, four o’clock). Pupils tell whether the angle made by the hands of the clock are bigger than/ smaller than/ equal to a right angle (for example, at three o’clock, the hands of the clock form a right angle).
2.
The teacher tells a specified time, and pupils set the clock accordingly.
Pupils have to determine whether the angles made by the hands of the clock are bigger than/ smaller than/ equal to a right angle.
Questions for Discussion:
1.
When the hour hand of a clock turns half a round, how many right angles has it turned?
2.
When the hour hand of a clock turns a complete round, how many right angles has it turned?
Generic Skills Fostered:
Communication Skills
Critical Thinking Skills
Numeracy Skills
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Recognise Right Angles
Reference:
Wilson, P.S. & Adams, V.M. (1992). A Dynamic Way To Teach Angle And
Angle Measure. Arithmetic Teacher , Vol. 39(5), 6-13.
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