Angles LO To identify right angles acute angles

Angles LO: To identify right angles, acute angles and obtuse angles

Right Angles • A right angle is an angle which measures 90° • Have a look around you. Can you see any nearby? There will be lots of right angles in your house.

Acute Angles • Acute angles measure less than 90° • Acute angles are SMALLER than 90° • Acute angle < 90° • I like to remember it by ‘cute’ meaning small • These may be harder to find in your house! Perhaps you could make an acute angle by partly opening a door, book or box?

Obtuse Angles • Obtuse angles measure more than 90° • Obtuse angles are • Obtuse angles > LARGER than 90° • If you open the door, book or box further than a right angle, you will create an obtuse angle!

Introduction Sort the angles. Smaller than a right angle (acute) Right angle Larger than a right angle (obtuse) Y 4 © Classroom Secrets Limited

Varied Fluency 1 Find all of the obtuse angles. Can you explain how you know they are obtuse? Y 4 © Classroom Secrets Limited

Varied Fluency 2 Use the symbols < or > to make the statements correct. obtuse angle ° 90 acute angle 90° Y 4 © Classroom Secrets Limited

Varied Fluency 2 Use the symbols < or > to make the statements correct. obtuse angle acute angle > ° 90 Y 4 © Classroom Secrets Limited

Reasoning 1 Which angle is the odd one out? Explain your answer. Y 4 © Classroom Secrets Limited

Reasoning 1 Which angle is the odd one out? Explain your answer. This angle is acute while all the others are right angles. Y 4 © Classroom Secrets Limited

Problem Solving 1 Match the angles which will still be acute when they are combined. 10° 12° 20° 79° 60° 65° Y 4 © Classroom Secrets Limited

Problem Solving 1 Match the angles which will still be acute when they are combined. 10° 12° 20° 79° 60° 65° Y 4 © Classroom Secrets Limited

Problem Solving 2 Using the digits below, can you create more obtuse or acute angles? 6 1 0 8 Y 4 © Classroom Secrets Limited

Problem Solving 2 Using the digits below, can you create more obtuse or acute angles? 6 1 0 8 2 -digit acute possibilities: 61°, 60°, 68°, 16°, 10°, 18°, 86°, 81°, 80° 3 -digit obtuse possibilities: 108°, 106°, 160°, 168° There are more acute than obtuse angles possible. Y 4 © Classroom Secrets Limited