Year 3 English · Key Stage 2 · Vocabulary, grammar and punctuation – English Appendix 2

Year 3 prefixes, a or an and word families

Year 3 grammar looks closely at how words are built and how they are related. Children learn to form nouns using prefixes such as super-, anti- and auto-, to choose between a and an depending on the word that follows, and to see how words belong to word families that share a meaning and a pattern of spelling. They also learn the terms for talking about this: word family, prefix, consonant, consonant letter, vowel and vowel letter.

Prefixes, a or an, and word families, explained

A prefix is a group of letters added to the start of a word that changes its meaning. In Year 3 children use a range of prefixes to form nouns, such as super- (supermarket, superstar), anti- (antifreeze, antibody) and auto- (autograph, autobiography). Knowing what a prefix means unlocks lots of words at once: super- means above or more than, anti- means against, and auto- means self, so an autograph is a person’s own signature and an autobiography is the story of a life written by that person. The curriculum gives super-, anti- and auto- as examples, and schools choose which other prefixes to teach alongside them.

A prefix does not change the spelling of the word it is added to. Dis + appear makes disappear, with one s, because the root begins with a. Dis + solve makes dissolve, with two s letters, because the prefix ends in s and the root starts with s. Children learn to split a word into prefix and root, and that spotting the prefix helps both reading and spelling.

The choice between a and an depends on the word that follows. Children learn that a comes before a word beginning with a consonant (a rock, a garden) and an comes before a word beginning with a vowel (an open box, an apple). In the curriculum, consonant and vowel mean sounds, while consonant letter and vowel letter mean the letters that are written. The vowel letters are a, e, i, o and u, and the other letters are consonant letters. For most words the first letter and the first sound match, so looking at the letter works. A few words show that the sound is what counts: we say an hour, because the h is silent and the word begins with a vowel sound, and a unicorn, because it begins with a y sound, which is a consonant sound.

A word family is a group of words that are related in form and in meaning, because they are built from the same root. Solve, solution, solver, dissolve and insoluble are one family. Seeing the family helps children work out the meaning of an unfamiliar word and spell it. Sign, signal and signature are a good example: the g is silent in sign but sounded in signal and signature, so knowing they belong together reminds you it is there.

Alongside these ideas, Year 3 children learn to use the correct terminology: word family, prefix, consonant, consonant letter, vowel and vowel letter. The two pairs of terms exist because letters and sounds are not the same thing. A letter is what you write, a sound is what you say, and an hour and a unicorn show that they do not always match. Teachers aim to teach all of this through reading and writing real sentences, not as isolated labels.

Words your child will hear

Prefix: Letters added to the start of a word to change its meaning, such as super- in superstar.
Root word: The word a prefix or ending is added to, such as market in supermarket.
Word family: Words that share a root and a related meaning, such as act, action, actor and react.
Vowel letter: One of the letters a, e, i, o, u.
Consonant letter: Any letter of the alphabet that is not a vowel letter.
Noun: A word for a person, place, thing or idea, such as autograph.
Vowel and consonant: The two kinds of speech sound. Whether a word starts with a vowel sound or a consonant sound decides a or an.

What the National Curriculum says

The programme of study for Year 3 says:

Pupils should be taught formation of nouns using a range of prefixes
Pupils should be taught use of the forms a or an according to whether the next word begins with a consonant or a vowel
Pupils should be taught word families based on common words, showing how words are related in form and meaning
Pupils should be taught to recognise and use the grammatical terminology: word family, prefix, consonant, consonant letter, vowel, vowel letter

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

Try it: a or an, and building a word family

Fill the gaps with a or an: “I saw ___ eagle on ___ rock near ___ old barn.” Then build a word family from the word friend.

Look at the word after each gap. Eagle begins with e, a vowel letter, so the first gap is an. Rock begins with r, a consonant letter, so the second gap is a. Old begins with o, a vowel letter, so the third gap is an.
```
an eagle
a rock
an old barn
```
Listen as well as look. The rule is really about the first sound, and for these three words the first letter and the first sound match. Say the phrases aloud: “a eagle” is awkward to say and “an rock” sounds odd.
Now the word family. Start with the root friend and think of words built on it: friendly, friendship, unfriendly, befriend.
Explain how each is related. All the words keep the spelling of friend, and all are about people getting on well. Unfriendly has the prefix un- meaning not, and befriend has the prefix be- and means to become a friend to someone.
Make a noun with a prefix. Add super- to market to make supermarket, or auto- to graph to make autograph. The root keeps its spelling.

“I saw an eagle on a rock near an old barn.” The friend family includes friendly, friendship, unfriendly and befriend.

Common mistakes and how to help

Changing the spelling of the root when adding a prefix: “dissapear” or “disolve”

Children try to spell the whole word by sound, and the double s in dissolve or the single s in disappear is easy to mix up.

What helps: Split the word into its parts. Dis + appear has one s from the prefix, and dis + solve has two, one from each part. Neither part changes.

Saying or writing “a apple” or “a egg”

Children are learning a is the short word, and they do not always stop to hear the clash.

What helps: Say the phrase out loud both ways. Link a to consonant sounds and an to vowel sounds, and sort pictures or objects into two piles.

Going by the first letter rather than the first sound: “a hour” or “an unicorn”

Children usually check the first letter, which works for most words. A few words begin with a letter that does not match the first sound.

What helps: Listen for the first sound. Hour begins with a vowel sound, so it is an hour. Unicorn begins with a y sound, so it is a unicorn. Keep a short list of these and add to it.

Assuming that words which look alike belong to the same family

Words sharing letters seem related, but a word family depends on meaning as well as spelling. Star and start share letters and are unrelated.

What helps: For each pair, ask: does the meaning link? Can you explain it in a sentence? Act and action both involve doing, so they pass. Star and start do not.

How to help at home

Prefix hunt. On a trip to the supermarket, look for words that begin with super-, anti- and auto-, such as supermarket, superstore and antibacterial wipes. Talk about what the prefix tells you about the word.
Draw a word family tree. Write a root word at the base of a tree, such as play, and add branches for related words: player, playful, replay, playground, playtime. Ask your child what the words have in common.
A or an sort. Collect a few household objects, or draw them, and sort them into two piles for a and an: an egg, a spoon, an umbrella, a sock, an orange. Add tricky ones such as an hour or a uniform when they are ready.
Take it apart. Choose a long word from your child’s reading and cut it into prefix and root with a pencil line. Ask what the prefix means and what the root means on its own.

Updated 20 October 2026.