Measurement

Angles & Right Angle Comparison

1

Match Angle Names

Draw a line from each angle type to its description.

Acute angle
Right angle
Obtuse angle
Straight angle
Exactly 90°
Less than 90°
Exactly 180°
Greater than 90° but less than 180°
2

Sort the Angles (Set A)

Sort each angle into the correct column.

45°
90°
120°
30°
90°
150°
75°
110°
Acute
Right
Obtuse
3

Sort the Angles (Set B)

Sort each angle.

60°
90°
135°
15°
100°
89°
91°
170°
Acute
Right
Obtuse
4

Name That Angle (Set A)

Circle the correct name for each angle.

An angle of 60°

Acute
Right
Obtuse

An angle of 135°

Acute
Right
Obtuse

A corner of a book

Acute
Right
Obtuse

An angle of 89°

Acute
Right
Obtuse

An angle of 91°

Acute
Right
Obtuse
5

Name That Angle (Set B)

Circle the correct name.

An angle of 10°

Acute
Right
Obtuse

An angle of 90°

Acute
Right
Obtuse

An angle of 175°

Acute
Right
Obtuse

An angle of 45°

Acute
Right
Obtuse

An angle of 120°

Acute
Right
Obtuse
6

Angles in Real Life (Set A)

Think about each object. Circle the type of angle it makes.

The corner of a window

Acute
Right
Obtuse

Clock hands at 10 o'clock

Acute
Right
Obtuse

Clock hands at 3 o'clock

Acute
Right
Obtuse

A slightly open laptop

Acute
Right
Obtuse
7

Angles in Real Life (Set B)

Circle the type of angle.

Clock hands at 6 o'clock

Acute
Right
Straight

A pizza slice tip

Acute
Right
Obtuse

Corner of a square tile

Acute
Right
Obtuse

An open pair of scissors

Acute
Right
Obtuse
8

Bigger or Smaller Than a Right Angle? (Set A)

Circle the correct answer.

50° compared to 90°

Smaller than right angle
Equal to right angle
Bigger than right angle

110° compared to 90°

Smaller
Equal
Bigger

90° compared to 90°

Smaller
Equal
Bigger

25° compared to 90°

Smaller
Equal
Bigger
9

Bigger or Smaller Than a Right Angle? (Set B)

Circle the correct answer.

145° compared to 90°

Smaller
Equal
Bigger

88° compared to 90°

Smaller
Equal
Bigger

90° compared to 90°

Smaller
Equal
Bigger

5° compared to 90°

Smaller
Equal
Bigger
10

Match Angles to Descriptions

Draw a line to match.

Less than 90°
Exactly 90°
Between 90° and 180°
Exactly 180°
Right angle
Obtuse angle
Acute angle
Straight angle
11

Match Angles to Everyday Objects

Draw a line from each angle type to an object that shows it.

Acute angle
Right angle
Obtuse angle
Straight angle
A ruler lying flat
Corner of a desk
An open book (almost flat)
A pizza slice tip
12

Angles That Make 90°

Two angles add to a right angle (90°). Find the missing angle.

90
30
?
90
?
45
90
60
?
90
?
10
90
75
?
13

Angles That Make 180°

Two angles on a straight line add to 180°. Find the missing angle.

180
90
?
180
?
60
180
120
?
180
?
45
180
150
?
14

Angle Sequences

Fill in the missing angles. Each step adds the same amount.

30
90
120
?
45
90
135
?
?
10
20
40
50
?
15

How Many Right Angles in the Shape?

Circle the correct number of right angles.

Rectangle

2
3
4

Square

2
3
4

Equilateral triangle

0
1
3

Right-angled triangle

0
1
2
16

Classify Angles (Write the Type)

Write whether each angle is acute, right, obtuse, or straight.

35° is a(n) ___ angle

90° is a(n) ___ angle

155° is a(n) ___ angle

180° is a(n) ___ angle

72° is a(n) ___ angle

108° is a(n) ___ angle

17

Sort: Less, Equal, or Greater Than 90°

Sort each angle.

45°
90°
135°
60°
120°
90°
10°
175°
Less than 90°
Equal to 90°
Greater than 90°
18

Count the Right Angles

Count how many right angles are shown. Write the number.

?
?
?
19

Count the Right Angles (Set B)

Count the right angles in each shape.

?
?
?
?
20

Angle Type? (Set C)

Circle whether the angle is acute, right, or obtuse.

30°

Acute
Right angle
Obtuse

90°

Acute
Right angle
Obtuse

150°

Acute
Right angle
Obtuse

85°

Acute
Right angle
Obtuse
21

Angle Type? (Set D)

Circle the angle type.

Acute
Right angle
Obtuse

179°

Acute
Right angle
Obtuse

45°

Acute
Right angle
Obtuse

91°

Acute
Right angle
Obtuse
22

True or False? (Angles – Set B)

Circle TRUE or FALSE.

An acute angle is less than 90°

TRUE
FALSE

An obtuse angle is less than 90°

TRUE
FALSE

A right angle is exactly 90°

TRUE
FALSE

A straight line makes an angle of 180°

TRUE
FALSE
23

True or False? (Angles – Set C)

Circle TRUE or FALSE.

A square has 4 right angles

TRUE
FALSE

All triangles have a right angle

TRUE
FALSE

A circle has no angles

TRUE
FALSE

An equilateral triangle has 3 equal angles of 60°

TRUE
FALSE
24

Match Angles to Types (Set A)

Draw a line from each angle to its type.

45°
90°
120°
10°
170°
Right angle
Acute
Obtuse
Acute
Obtuse
25

Match Angles to Types (Set B)

Draw a line to match.

89°
91°
180°
135°
Acute
Obtuse
Straight angle
Acute
Obtuse
26

Sort: Acute, Right, or Obtuse? (Set C)

Sort each angle.

72°
90°
108°
15°
165°
55°
Acute (< 90°)
Right (= 90°)
Obtuse (> 90°)
27

Sort: Acute, Right, or Obtuse? (Set D)

Sort each angle.

89°
90°
91°
35°
145°
60°
Acute
Right angle
Obtuse
28

Angles Adding to 90° (Complementary)

Two angles add up to 90°. Find the missing angle.

90
30
?
90
?
45
90
60
?
90
?
75
90
10
?
29

Angles Adding to 180° (Supplementary)

Two angles on a straight line add up to 180°. Find the missing angle.

180
90
?
180
?
60
180
135
?
180
?
110
180
45
?
30

Identify Angles in Shapes

Name the type of angle at each corner.

A square has ___ angles at each corner (acute/right/obtuse).

An equilateral triangle has ___ angles at each corner.

A regular hexagon has ___ angles at each corner.

Name a shape that has both acute and obtuse angles:

31

Angles in Everyday Life

Identify angles in the real world.

Name 3 things with right angles:

Name 2 things with acute angles:

Name 2 things with obtuse angles:

32

Angle Sequences

Continue the pattern of angles.

30
60
90
120
?
?
10
20
30
40
?
?
?
180
135
90
45
?
33

Compare Angles (Set A)

Circle the larger angle.

Which is larger?

45°
135°

Which is larger?

90°
89°

Which is larger?

60°
120°

Which is larger?

175°
34

Compare Angles (Set B)

Circle the larger angle.

Which is larger?

30°
150°

Which is closer to a right angle?

85°
100°

Which is larger?

91°
89°

Which is larger?

179°
35

Angles in Our Classroom

Count objects with each type of angle.

Right angles
Acute angles
Obtuse angles
1

Which type of angle is most common in the classroom?

2

How many angles were found altogether?

3

Can you think of where the obtuse angles might be?

36

Estimate the Angle (Set A)

Circle the best estimate for each angle.

A slightly open door

About 20°
About 45°
About 90°

A door open halfway

About 45°
About 90°
About 135°

A door wide open

About 90°
About 135°
About 180°
37

Estimate the Angle (Set B)

Circle the best estimate.

Corner of an equilateral triangle

30°
60°
90°

Corner of a square

60°
90°
120°

Corner of a regular hexagon

90°
120°
150°
38

Draw and Label Angles (Set A)

Draw an example of each type of angle. Label it.

Draw an acute angle:

Draw here

Draw a right angle:

Draw here

Draw an obtuse angle:

Draw here
39

Draw and Label Angles (Set B)

Draw angles of approximately the given size.

Draw an angle of about 45°:

Draw here

Draw an angle of about 120°:

Draw here

Draw a straight angle (180°):

Draw here
40

Angles in Shapes

Answer each question about angles in shapes.

How many right angles does a rectangle have?

Name a shape that has only acute angles.

Can a triangle have an obtuse angle? If yes, draw one.

Draw here

Can a triangle have two right angles? Explain why or why not.

41

Angles in a Turn

Circle the correct answer.

A quarter turn = ?

45°
90°
180°

A half turn = ?

90°
180°
270°

A full turn = ?

180°
270°
360°

A three-quarter turn = ?

180°
270°
360°
42

Match Turns to Degrees

Draw a line to match.

Quarter turn
Half turn
Three-quarter turn
Full turn
180°
360°
90°
270°
43

Angle Reasoning

Answer these questions about angles.

The angles in a triangle add up to 180°. If two angles are 60° and 70°, what is the third?

A right angle is 90°. Two right angles together make ___°.

If you turn 90° clockwise three times, how many degrees have you turned in total?

44

Challenge: Angle Puzzles

Solve these puzzles.

An angle is 30° less than a right angle. What is the angle?

Two equal angles together make a straight angle (180°). What is each angle?

Clock hands at 1 o'clock form a 30° angle. What angle do they form at 4 o'clock?

45

Home Activity: Angle Hunt

Find angles around your home!

  • 1Find 3 right angles in your home (hint: corners of doors, books, tables).
  • 2Open a door slightly — is the angle acute or obtuse? Open it wider — what now?
  • 3Look at clock hands at different times. List which make acute, right and obtuse angles.
  • 4Make angles with your arms. Can a friend guess if it is acute, right or obtuse?
46

Match Angle Type to Description

Draw a line from each angle type to its description.

Acute angle
Right angle
Obtuse angle
Straight angle
Reflex angle
Exactly 180°
Between 90° and 180°
Between 180° and 360°
Less than 90°
Exactly 90°
47

Identify the Angle Type (Set A)

Circle the type of angle for each measurement.

A 45° angle is:

Acute
Right
Obtuse

A 120° angle is:

Acute
Right
Obtuse

A 90° angle is:

Acute
Right
Obtuse

A 175° angle is:

Right
Obtuse
Reflex
48

Angles in Polygons

Find the sum of angles in each polygon.

The angles in a triangle add to ___°. In an equilateral triangle, each angle = ___°

The angles in a rectangle add to ___°. Each angle = ___°

A regular pentagon has 5 equal angles. Total = 540°. Each angle = ___°

49

Sort Angles: Acute, Right, Obtuse or Reflex?

Sort each angle into the correct column.

35°
90°
145°
270°
88°
200°
Acute (< 90°)
Right (= 90°)
Obtuse (90°–180°)
Reflex (> 180°)
50

Measuring Angles

Estimate the angle shown, then explain how to check with a protractor.

A clock shows 3 o'clock. The angle between the hands is ___°.

A clock shows 6 o'clock. The angle is ___°. This type of angle is called ___.

A clock shows 9 o'clock. The angle is ___°. This type is ___.

51

Angles on a Straight Line

Angles on a straight line add to 180°. Find the missing angle.

One angle is 70°. The other angle = ___°

One angle is 135°. The other angle = ___°

Three angles on a line: 45°, 90°, ___°

Two equal angles on a line. Each angle = ___°

52

Angles at a Point

Angles at a point add to 360°. Find the missing angle.

Three angles at a point: 90°, 120°, ___°

Two angles at a point: 215°, ___°

Four equal angles at a point. Each angle = ___°

53

Angles in Triangles

Circle the correct answer.

A triangle has angles of 60° and 80°. The third angle is:

40°
50°
60°

A right triangle has one angle of 90° and another of 35°. The third is:

45°
55°
65°

Can a triangle have two obtuse angles?

Yes
No
Sometimes

An equilateral triangle has all angles equal. Each angle is:

45°
60°
90°
54

Trace and Label Angle Types

Trace each shape and label all angles as acute, right or obtuse.

Right-angled triangle3 sides
Rectangle4 sides
Obtuse triangle3 sides
Rhombus4 sides
55

Angles Found in the Classroom

Tally how many of each angle type you can find in the classroom.

ItemTallyTotal
Acute angles
Right angles
Obtuse angles
Straight angles
56

Compass Directions and Angles

Use compass directions to think about angles.

Turning from North to East is a ___° turn (clockwise).

Turning from North to South is a ___° turn.

Turning from East to West clockwise is ___°. Anti-clockwise is ___°.

What direction are you facing after turning 270° clockwise from North?

57

Angles in Real Life

Find and describe angles in real life.

Name three objects in your home that have right angles.

Name three objects that have acute angles.

Why do builders need to know about right angles? Give two reasons.

58

Challenge: Angle Puzzles

Solve these angle puzzles.

I am an angle in a regular hexagon. All 6 angles are equal and add to 720°. I am ___°.

Two angles are supplementary (add to 180°). One is three times the other. Find both angles.

An angle and its complement add to 90°. One angle is 25°. What is the complement?