# Sort the Angles: Acute or Obtuse

In this worksheet, students sort angles into acute or obtuse.

Key stage:  KS 2

Curriculum topic:   Geometry: Properties of Shapes

Curriculum subtopic:   Identify Acute/Obtuse Angles

Difficulty level:

### QUESTION 1 of 10

This worksheet is about spotting acute and obtuse angles.

Example

Sort the angles into acute and obtuse.

(a) (b) (c)

(d) (e) (f)

Acute angles: c, d, e.

These are less than 90° (a right angle).

Obtuse angles: a, b, f.

These are more than 90° (a right angle) but less than 180° (a straight line).

Want to understand this further and learn how this links to other topics in maths?
Why not watch this video?

Sort the angles into acute and obtuse.

(a) (b) (c)

(d) (e) (f)

 Acute Obtuse (a) (b) (c) (d) (e) (f)

Sort the angles into acute and obtuse.

(a) (b) (c)

(d) (e) (f)

 Acute Obtuse (a) (b) (c) (d) (e) (f)

Sort the angles into acute and obtuse.

(a) (b) (c)

(d) (e) (f)

 Acute Obtuse (a) (b) (c) (d) (e) (f)

Angles (a) (b) and (e) are all obtuse.

Is this statement correct?

(a) (b) (c)

(d) (e) (f)

Correct

Incorrect

Is this statement correct?

50% of the angles shown below are acute angles

(a) (b) (c)

(d) (e) (f)

Correct

Incorrect

Is this statement correct or incorrect?

Angles (a) (b) and (d) are all greater than 90 &deg;

(a) (b) (c)

(d) (e) (f)

Correct

Incorrect

Is the following statement correct or incorrect?

There is only one angle below that is less than 180 &deg;

(a) (b) (c)

(d) (e) (f)

Correct

Incorrect

Sam thinks that (a) (c) and (f) are not classified as acute angles, is he correct?

(a) (b) (c)

(d) (e) (f)

Correct

Incorrect

Sneha thinks that the following angles are classified in the following ways:

(a) obtuse

(b) obtuse

(c) obtuse

(d) acute

(e) acute

(f) obtuse

Sneha is wrong with one of these classifications.  Which angle has she miscategorised?

(a)  (b)  (c)

(d)  (e)  (f)

(a)

(b)

(c)

(d)

(e)

(f)

Last question, let's check we really understand how to classify angles!

(a)  (b)  (c)

(d)  (e)  (f)
 Acute Obtuse (a) (b) (c) (d) (e) (f)
• Question 1

Sort the angles into acute and obtuse.

(a) (b) (c)

(d) (e) (f)

 Acute Obtuse (a) (b) (c) (d) (e) (f)
EDDIE SAYS
How did you get on here? Acute angles are less than 90 degrees (right angle). It helps to think about where the right angle would be in each drawing. Obtuse angles are greater than 90 degrees, but less than 180 degrees (straight line).
• Question 2

Sort the angles into acute and obtuse.

(a) (b) (c)

(d) (e) (f)

 Acute Obtuse (a) (b) (c) (d) (e) (f)
EDDIE SAYS
Did you imagine the line going straight up to form a right angle? Acute angles are less than 90 degrees (right angle). Obtuse angles are greater than 90 degrees, but less than 180 degrees (straight line).
• Question 3

Sort the angles into acute and obtuse.

(a) (b) (c)

(d) (e) (f)

 Acute Obtuse (a) (b) (c) (d) (e) (f)
EDDIE SAYS
Are you getting the hang of this now? Acute angles are less than 90 degrees (right angle). Obtuse angles are greater than 90 degrees, but less than 180 degrees (straight line).
• Question 4

Angles (a) (b) and (e) are all obtuse.

Is this statement correct?

(a) (b) (c)

(d) (e) (f)

Incorrect
EDDIE SAYS
This sentence was incorrect. (a) and (b) are both greater than 90 degrees, but angle (e) is acute as it is smaller than 90 degrees.
• Question 5

Is this statement correct?

50% of the angles shown below are acute angles

(a) (b) (c)

(d) (e) (f)

Correct
EDDIE SAYS
This statement was correct! There are 3 acute angles - (c) (d) and (f) There are 3 obtuse angles - (a) (b) and (e) This means that half of the angles are acute, which can also be written as 50%.
• Question 6

Is this statement correct or incorrect?

Angles (a) (b) and (d) are all greater than 90 &deg;

(a) (b) (c)

(d) (e) (f)

Correct
EDDIE SAYS
This statement was correct. We know that obtuse angles are angles that are greater than 90 ° When we look at the angles (a) (b) and (d) we can see they are all obtuse.
• Question 7

Is the following statement correct or incorrect?

There is only one angle below that is less than 180 &deg;

(a) (b) (c)

(d) (e) (f)

Incorrect
EDDIE SAYS
Did you get this one right? All of the angles above are less than 180 ° as they are less than the angle of a straight line. Always start with the rules we know about angles and you won't go too far wrong!
• Question 8

Sam thinks that (a) (c) and (f) are not classified as acute angles, is he correct?

(a) (b) (c)

(d) (e) (f)

Correct
EDDIE SAYS
Did the wording of the question catch you out? It was worded in a slightly confusing way to see if you had remembered your rules about angles! Let's first look at the angles mentioned and classify them. (a) (c) and (f) are all obtuse angles. Therefore, these angles are not classified as acute.
• Question 9

Sneha thinks that the following angles are classified in the following ways:

(a) obtuse

(b) obtuse

(c) obtuse

(d) acute

(e) acute

(f) obtuse

Sneha is wrong with one of these classifications.  Which angle has she miscategorised?

(a)  (b)  (c)

(d)  (e)  (f)

(c)
EDDIE SAYS
To work this one out it is best to go through each angle one at a time. If you do this systematically you should find one answer from Sneha that you think is wrong. Did you agree that she has miscategorised (c)?
• Question 10

Last question, let's check we really understand how to classify angles!

(a)  (b)  (c)

(d)  (e)  (f)
 Acute Obtuse (a) (b) (c) (d) (e) (f)
EDDIE SAYS
Hopefully, this one was a nice easy one to finish with, and show you what a good angle classifier you are! Remember: Acute angles are less than a right angle. Obtuse angles are more than a right angle but less than a straight line. Great work angle sorter! Why not try another activity to test out your understanding in the world of angles!
---- OR ----

Sign up for a £1 trial so you can track and measure your child's progress on this activity.

### What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started