Prefixes, suffixes, Standard English and formality

Prefixes and what they mean

A prefix is a group of letters added to the start of a word to change its meaning. The root word's spelling never changes, which is why double letters appear when the prefix ends with the letter the root begins with: dis + satisfied = dissatisfied, mis + spell = misspell.

Many prefixes have reliable meanings, and knowing them lets children work out words they have never seen:

Which prefix fits?

Several prefixes mean “not”, so children have to choose. The in- prefix changes form to suit the next letter, which gives a pattern children can actually use:

• impossible, immatureim- before m and p.
• irregular, irrelevantir- before r.
• illegal, illogicalil- before l.
• unpossibleSounds plausible, but the word is impossible.

Suffixes

A suffix goes on the end of a word and often changes its word class. Kind (adjective) becomes kindness (noun); solid (adjective) becomes solidify (verb); hope (noun or verb) becomes hopeful (adjective). The SATs often ask children to add a suffix to make a word of a particular class, so they need to know which suffixes make nouns (-ness, -ment, -ity), verbs (-ise, -ify, -ate) and adjectives (-ful, -less, -ous, -able).

Adding a suffix can change the spelling of the root: happy becomes happiness, hope becomes hoping, stop becomes stopped. The spelling side of this is covered in the guide to adding suffixes.

Synonyms and antonyms

Synonyms have the same or very similar meanings (big, large, enormous). Antonyms have opposite meanings (ancient, modern). Questions in the SATs usually give a word in a sentence and ask for a synonym or antonym that fits that context, which matters because many words have more than one meaning.

The test for a synonym is to swap it into the sentence. If the meaning stays the same and the sentence still sounds right, it works. Bright could mean clever or shiny, and only one of those fits a bright pupil.

Standard English

Standard English is the variety of English used in formal writing and speech, with agreed grammar. Regional dialects are not wrong, just different, but the SATs and formal writing expect the Standard form.

• We was late.Standard English: We were late.
• I done it already.Standard English: I did it already or I have done it.
• Them books are mine.Standard English: Those books are mine.
• I ain't got none.Standard English: I haven't got any.

Reading aloud doesn't always help here, because children are used to hearing the non-standard form. Teaching the specific forms explicitly, and explaining that dialect has its place, works better than correcting each instance on its own.

Formal and informal language

Formal language is for official letters, reports and speeches; informal language is for friends and family. Formal writing avoids contractions, slang and chatty phrasal verbs, and may use the passive voice and the subjunctive.

How these are tested in the SATs

• Add a prefix to make a word mean the opposite, or explain what a prefix means.
• Add a suffix to change a word into a given word class.
• Choose a synonym or antonym for a word in context.
• Correct a sentence into Standard English.
• Tick the most formal version of a sentence, or replace an informal phrase.

Common mistakes

• Dropping a letter where prefix and root meet: mispell, disatisfied.
• Choosing a prefix that sounds right but isn't the real word.
• Giving a synonym for a different meaning of the word.
• Thinking formal just means longer words, and missing contractions and phrasal verbs.

Teaching ideas

Prefix families

Give each group a prefix and five minutes to list as many words as they can that use it. Then check each word: is it really the prefix, or just the same letters (uncle, display)?

Word-class transformer

Start with a root word and ask pupils to turn it into a noun, a verb, an adjective and an adverb using suffixes. Hope gives hopefulness, hoping, hopeful, hopefully.

Two letters

Pupils write the same message twice: once to a friend and once to the head teacher. They then list every change they made and sort the changes into vocabulary, contractions and grammar.

Dialect detectives

Share examples of regional dialect from books, songs or TV. Discuss where each is used and what the Standard English version would be, so children see Standard English as a choice for the right situation.

Try it: five quick questions

SATs-style questions to use as a starter or a quick check. Tap to see each answer.

1. Add a prefix to make the opposite of legal.

   Show answer

   illegal

2. What does the prefix sub- mean in submarine?

   Show answer

   Under.

3. Add a suffix to turn enjoy into a noun.

   Show answer

   enjoyment

4. Rewrite in Standard English: We was going to the shops.

   Show answer

   We were going to the shops.

5. Which is the most formal? Can you find out when it starts? / Please could you establish when it begins?

   Show answer

   Please could you establish when it begins?