Vocabulary Development: Uses of Prefix – JSS1 English Lesson Note (First Term)

A prefix is a group of letters added to the beginning of a word to form a new word with a different meaning. The spelling of the original word does not change. In this lesson, the prefixes un-, in-, il-, im-, ir- and dis- are added to words to give the opposite meaning, for example legal becomes illegal.

Behavioural objectives

By the end of the lesson, students should be able to:

• state what a prefix is;
• add the correct prefix to a word to give its opposite meaning;
• choose between il-, in-, im-, ir- and un- by looking at the first letter of the word;
• use words with prefixes correctly in sentences.

What is a prefix?

A prefix comes before the root word. It changes the meaning of the root word but does not change its spelling. Words formed in this way increase our vocabulary.

Examples of word formation

Which prefix do we use?

The prefixes below all give a negative or opposite meaning. The first letter of the root word often tells us which one to use.

There is no rule that fits every word, so students should learn each new word with its prefix.

Prefixes in sentences

• It is illegal to drive without a licence.
• Indiscipline in school can spoil a pupil’s future.
• We wore informal clothes to the picnic.
• It was unfortunate that the match was cancelled.
• The inefficient worker was always late with his report.
• Bola was unhappy because she lost her pen.

Teaching steps

1. Write the word legal on the board and ask students for its opposite.
2. Add il- in front of it and explain that the new word is illegal.
3. Show the other examples in the first table in the same way.
4. Teach the table of rules, with students giving more examples for each prefix.
5. Ask students to use some of the new words in sentences.

Evaluation

Add the correct prefix (il, im, in, ir, un or dis) to each word to give its opposite meaning.

1. ___possible
2. ___honest
3. ___regular
4. ___happy
5. ___literate
6. ___polite

Answer key: 1. impossible, 2. dishonest, 3. irregular, 4. unhappy, 5. illiterate, 6. impolite.

Assignment

Add the correct prefix to each word to give its opposite meaning.

1. ___obey
2. ___able
3. ___perfect
4. ___responsible
5. ___correct
6. ___fair

Answer key: 1. disobey, 2. unable, 3. imperfect, 4. irresponsible, 5. incorrect, 6. unfair.