Short /ʌ/, two different long values, a /ʊ/ set after p and b, and a job as a silent partner to q and g.
Letter sounds
u LETTER_U_01
Useful pattern · Medium reliability · Common · Early · Reading
/ʌ/ short u: cup, sun, bug
/juː/ long u with a glide: cube, music, human
/uː/ long u without the glide: rule, June, flute
/ʊ/ the vowel of put: put, push, full
Silent: queen, guess, guitar
Where Wiggler teaches it: Skill 2: CVC Word Mastery · Skill 6: Magic e · Skill 12: Multisyllable Decoding
Child explanation
U says /ʌ/ in cup. With an e on the end it says its name: cube. But in put and push it makes a different sound again.
The rule
Short /ʌ/ in a closed syllable. With silent e or in an open syllable, u is long — /juː/ after most consonants, /uː/ after r, l, j and in many accents after t, d and n. After p, b and f a small set takes /ʊ/ instead.
What is really going on
Long u is the only English long vowel that is phonetically two things: /juː/ in cube, music and human, and plain /uː/ after /r/, /l/ and /dʒ/, where the glide is systematically lost (rule, blue, June). Whether the glide survives after /t/, /d/ and /n/ is one of the sharpest divisions between accents. The /ʊ/ of put, push, bush and full is a separate small set, conditioned by a neighbouring labial consonant.
Position in the word
Middle of a word — Short in a closed syllable. For example: cup, sun, bug, jump.
After a consonant — After q, and in guess and guitar, u is silent — it is marking the consonant, not making a sound. For example: queen, quick, guess, guest, guitar.
Unstressed syllable — Schwa. For example: support, album, circus.
Made-up words that follow the rule. A child who reads these has the pattern rather than the vocabulary.
blud, shupe, frune
Exceptions
u as /ʊ/: put, push, pull, full, bush, bull, pudding, sugar. A small set conditioned by the p, b, f and l around it.
u carrying no sound: queen, quiet, guess, guide, guitar, guard. After q it is part of the qu unit; after g it marks the g as hard before e or i.
busy and bury: busy, business, bury. Two one-off spellings where u represents /ɪ/ and /e/.
Contrast pairs
cub versus cube — Closed versus silent e.
cut versus put — Short u versus the put family — same shape, different vowel.
cube versus rule — Long u with the glide versus without it.
Common reading mistakes
put: a child reads /pʌt/, rhyming with cut, where the word is /pʊt/. Short u applied to the put family.
queen: a child reads /kwuːiːn/, where the word is /kwiːn/. The u in qu decoded as a vowel.
Teacher note
Teach qu as one unit from the start so the u never has to be explained away. Put, push, pull and full are frequent enough to be worth teaching as a small family early. Do not correct a child for saying /tuːn/ or /tjuːn/ — both are standard, and which one they say is their accent rather than their reading.
Accent notes
General American — The /j/ glide is dropped after t, d, n, s and l: tune is /tuːn/, new is /nuː/, duke is /duːk/.
British English — The glide is kept in those words: /tjuːn/, /njuː/, /djuːk/.
Indian English — Generally keeps the glide, following British usage. Both are correct; a child should not be corrected for either.