NCERT Solutions: Angles as Turns
Page 32
Q. Can you recognise the child in the picture who has made a full turn? Who has made a half turn? How do you know? Discuss in class.
Ans: In the second image, child A is facing backward or has made a half turn, child B is facings lightly sideways or has made an acute angle, child C has made a full turn as he is facing in the same direction, and child D has made a quarter turn. Thus, child C has made a full turn and child A has make a half turn.
Q. Give examples of real-life situations where you observe turns.
Ans: 1. Riding a merry-go-round.
2. Opening a bottle cap.
3. Turning a doorknob to open a door.
4. Turning the handle of a bicycle or the steering wheel of a car.
5. Dancer making quarter, half, or full turns.
6. Turning a key in a lock.
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A giant wheel makes a full turn when it comes back to the starting position E.
Reema takes two half turns in the same direction. It is like a ______turn.
What happens if she takes 2 quarter turns in the same direction? It is like a ______turn.
What happens if she takes 4 quarter turns in the same direction? It is like a ____ turn.
Ans: Reema takes two half turns in the same direction. It is like a complete turn.
What happens if she takes 2 quarter turns in the same direction? It is like a half turn.
What happens if she takes 4 quarter turns in the same direction? It is like a complete turn.
Q. Write some of the everyday objects that involve turns. For example, taps, __________, __________, __________, __________, and __________.
Ans: Taps, door knobs, steering wheels, bottle caps, keys, and merry-go-rounds.
Q. What is the maximum possible turn in each of these cases? Check and tick.
Ans:
Q. Do any of the above objects make a half turn? Write their names below-
Ans: Yes. Door with hinge, and File cover make a half turn.
Q. Do any of the above objects make a full turn? Write their names below-
Ans: None of these objects make a full turn.
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Let Us Do
(a) Making a paper fan. Take a rectangular paper, fold every 2 cm as shown in the picture. Paste ice cream sticks as shown below to create a paper fan.
Use your paper fan to show different acute angles and obtuse angles.
Let us look at the turns made by the paper fan, keeping one side fixed.
Make an acute turn with the straws or fan. Continue to make another acute turn. Can the two acute turns together make another acute turn?
Ans: Yes, two acute angles together can make another acute turn.
For example,
Make a paper fan.
- Make less than a 1/4 turn (acute angle).
- Make less than a 1/4 turn (acute angle).
- Put one above the other.
- It is still less than a 1/4 turn (acute angle).
So, two acute turns together can make another acute turn.
(b) You might have built houses using the hard covers of notebooks or cardboard pieces. Look at the angles marked in the house. What angles are you able to see in this house?
Write your answers as right, acute or obtuse angle.
A: ______________ B: _____________
C: ______________ D: _____________
E: ______________ F: _____________
G: ______________ H: _____________
Ans: We can see acute, right and obtuse angles in this house.
A: Obtuse angle
B: Right angle
C: Acute angle
D: Acute angle
E: Acute angle
F: Right angle
G: Right angle
H: Obtuse angle
(c) Make a 5-sided shape with 2 right angles, 2 obtuse angles, and 1 acute angle in your notebook.
Ans:
One acute angle: ∠A
Two obtuse angles: ∠B and ∠E
Two right angles: ∠C and ∠D
(d) Look at the angle formation between the legs of these gymnasts. Identify whether the angles are acute, obtuse, right or straight.
Ans:
Angle Measuring Tool
Let us make our tool to measure turns.
(a) Cut out a circle from a tracing paper and fold it to make 8 equal parts. Attach a straw to the centre and mark the starting point as shown.
(b) Now, try this.
• Show a 
turn of the straw.
• Show a 
turn. Show a 
turn. Show a 
turn.
Ans: Turn the straw by two 1/8 part of the circle clockwise or anticlockwise.
Since two 1/8 makes a 1/4, turn the straw by two parts of the circle clockwise or anti-clockwise.
Turn the straw by three parts of the circle clockwise or anti-clockwise.
What angle have you made with a 
turn? A 
turn is half of a quarter turn.
Ans: Angle made with a 2/8 turn is a right angle.
Since, two 1/8 make a 1/4. So, a 1/8 turn is half of a quarter turn.
What angle have you made with a 
turn?
Ans: Turn the Straw by four 1/8 parts of the circle clockwise or anticlockwise.
So, the angle made with a 4/8 turn is a straight angle.
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Let Us Think
Q1. In the following circles, the end points of 1/2 , 1/4 , and 1/8 turns are shown. Draw arrows to show the starting points.
Ans: 
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Let Us Do
Q1. Guess the measures of each of the angles shown below. Then, check using your angle measuring tools. You may need to use a combination of measures. Also, state whether each of the angles is acute, right, or obtuse.
Ans:
Q2. Guess the measure of the turns made by the arrow in each of the following cases. Verify with a combination of angle measuring tools.
Ans:
Q3. Measure each angle in the given shapes. Write the measure of the angles in terms of turns and describe whether they are acute, obtuse or right angles.
Ans:
Q4. Draw angles for the given measures of turns using the given lines.
Ans:
Q5. Draw the angles formed by the following turns in your notebook.
Ans: 
Q6. Guess the measure of turns the minute hand of a clock makes in each of the following cases. The initial position of the minute hand is given. Draw the final position of the minute hand on the clock face. Discuss your reasoning in class.
Ans: (a) 1/4 turn.
(b) 1/2 turn.
(c) 3/4 turn.
(d) 1/12 × 60 = 5 minutes.
(e) 60 minutes.
(f) 1/6 × 60 = 10 minutes.
(g) 4/12 × 60 = 4 × 5 = 20 minutes.
Which direction?
In which direction do the hands of a clock move? The direction in which the hands of the clock move is called clockwise movement. The opposite movement is called anti-clockwise movement. The creatures below have made a quarter turn once. Tick the direction in which they have moved.
Ans:
Try these
Observe the direction of movement while opening a tap, unscrewing a lid or loosening a nut. Do they move clockwise or anti-clockwise?
Ans:
- To open a tap, we rotate it anti-clockwise.
- To unscrew a lid, we turn it anti-clockwise.
- To loosen a nut, we rotate it anti-clockwise.
So, in all these actions, the movement is anti-clockwise.
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Fun with Turns
Q1. The children in a class are playing a game in which the teacher tells them the direction in which they should rotate. Complete the table by filling the direction the children will face on completing the given turns. The starting direction is given in the table.
Ans:
Q2. Padma is facing the toy shop. What place will she face if she takes a half turn clockwise? What other way can she turn to face the same place?
Ans: Since, Padma is facing toy shop, a half turn clockwise means Padma will face the opposite direction. So, she will now face the Ice Cream cart.
She can also take a half turn anti-clockwise to face the same place i.e., Ice Cream cart.
FAQs on NCERT Solutions: Angles as Turns
| 1. What exactly is an angle as a turn and how do I understand it? |  |
| 2. How do I measure angles using turns in CBSE Class 5 mathematics? | |
| 3. What's the difference between clockwise and anticlockwise angles? | |
| 4. Why do we learn angles as turns instead of just memorising angle definitions? | |
| 5. Can I use the concept of angles as turns to solve geometry problems in my CBSE exams? | |
