Adding the prefix un-

Learning focus

Learn about how to add the prefix un- to make new words.

This lesson includes:

  • one video explaining how to use the prefix un-

  • three activities


Prefixes are a group of letters that change the meaning of a word when they are added to the start.

The prefix un- usually means not, so the new word means the opposite of the original.

For example:

  • unkind means ‘not kind’
  • unhappy means 'not happy'
  • unlocked means 'not locked'

In this Teacher Talk, Mr Smith explains all about how to use the prefix un- and shows you some examples.

Watch, listen carefully and join in with the activities.

Learn how to use the prefix un-.


You may need paper and a pen or pencil for some of these activities.

Activity 1

Let’s add un-!

Write out the words below adding un- to the start.
Then explain what the new word means.

The first one has been done for you:

1. certain = uncertain
This means not certain

2. sure =

3. happy =

4. tidy =

5. well =

You can check your answers using this answer sheet.

Activity 2

Let’s sort some words!

You cannot add un- to every word.
Read the words in the quiz. Click on the ones that you can add the prefix un- to.

Top tip!

Say the new word out loud. Does it sound right?

Activity 3

Let’s write some sentences!

Below is a list of five words you can add un- to.

Choose three words and add the prefix un- to them.

Now write three sentences using those words.

For example: It is unbelievable that you saw an alien!

  • safe

  • zip

  • friendly

  • believable

  • lock

Top tip!

Don’t forget to start your sentence with a capital letter and end it with a punctuation mark.

Where next?

In this lesson you have learned how to add the prefix un- to make new words.

To learn more about different types of prefixes and suffixes, take a look at:

Or you could practise your spelling, punctuation and grammar with the
Karate Cats!

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