OI

One sound, one position. Oi appears inside a word and oy at the end, and between them they cover nearly every /ɔɪ/ in English.

Diphthongs

oi TEAM_OI_01

Strong rule · High reliability · Common · Intermediate · Reading and spelling

• /ɔɪ/ oi: coin, point, join

Where Wiggler teaches it: Skill 10: Diphthongs & Variant Vowels

Child explanation

O and i together say /ɔɪ/, like in coin. You find oi in the middle of a word.

The rule

Oi represents /ɔɪ/ at the beginning or in the middle of a word. Oy does the same job at the end.

What is really going on

The /ɔɪ/ diphthong has the cleanest spelling distribution of any English vowel sound: oi medially, oy finally, and almost nothing else. It is a good example to give children of English behaving well, and a good place to show the medial/final pattern that ai/ay and au/aw also follow.

Position in the word

• Beginning of a word — Reliable. For example: oil, oink, ointment.
• Middle of a word — The usual position. For example: coin, point, join, noise.
• End of a word — Oi does not end English words; oy does.

Examples

Easy examples

coin, oil, join, point, boil

More examples

soil, spoil, voice, choice, noise, coil, toil, moist, avoid, poison, appoint

Pseudo-words

Made-up words that follow the rule. A child who reads these has the pattern rather than the vocabulary.

floin, shoit, proim

Contrast pairs

• coin versus con — Team versus single vowel.
• boil versus boy — Same sound, different position, different spelling.

Decodable sentences

• Join the coins in a coil.
• Do not spoil the soil with oil.
• I heard a noise and made a choice.

Teacher note

Teach oi and oy in one lesson. The position rule is exceptionless in practice and gives children a second clean example of the pattern they already met with ai and ay, which makes au/aw easy when it arrives.

Learn these first

• The five short vowels — a e i o u in a closed syllable — A single vowel with a consonant after it and nothing else is usually short. This is the rule that makes CVC words decodable.

Related rules

• OY — oy — The end-of-word partner to oi. Boy, toy, joy, enjoy — one sound, essentially no exceptions.
• AI — ai — Long a inside a word. Pairs with ay, which does the same job at the end — ai almost never ends an English word.
• AU — au — The /ɔː/ of haul and sauce, used inside a word. Pairs with aw, which does the same job at the end.

• Previous in Diphthongs: OU — ou — /aʊ/ in cloud is the main value, but ou also gives /ʌ/, /uː/, /ʊ/ and /ɔː/. One of the most variable teams in English.
• Next in Diphthongs: OY — oy — The end-of-word partner to oi. Boy, toy, joy, enjoy — one sound, essentially no exceptions.
• All reading rules

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