German ä, ö and ü are vowels with their own sounds, and the dots can change a word’s meaning or grammatical form. For ö and ü, keep the tongue forward while rounding the lips. Each vowel has long and short versions. If the characters are unavailable when typing, use ae, oe and ue rather than removing the dots.
Schon and schön are not interchangeable spellings. One is already; the other is beautiful. An umlaut can also mark a plural, as in Mutter → Mütter (mother → mothers). Those two dots are doing actual work.
The mouth movement
Vowel
How to start practising
Long / short examples
ä
Practise an open e-like vowel with a recording.
spät — late / hätte — would have
ö
Keep an e-like tongue position; round the lips.
schön — beautiful / können — can
ü
Keep an ee-like tongue position; round the lips.
Tür — door / müssen — must
These are physical starting instructions, not claims that German vowels equal English vowels. English has many accents, and the long and short German pairs differ in quality as well as duration. Short ü in müssen is not simply long ü played faster.
Why ö turns into o when you are not careful
Your lips may find the rounded shape easily, while your tongue retreats towards the position for o. Keep the front of the tongue forward. Start with an e-like sound, round your lips without moving your tongue back, and compare with schön in a dictionary recording.
For ü, try a long ee-like sound, then round the lips while keeping the tongue position. Avoid making an English “you”: German ü is one vowel, not a y followed by oo.
Useful contrasts
Mutter / Mütter contrasts mother and mothers. Schon / schön contrasts already and beautiful. Konnte / könnte contrasts could in a past ability statement with a conditional or tentative could. Sound and grammar meet in the same small change.
Practise each pair in a sentence rather than indefinitely making isolated noises: Das ist meine Mutter. — That is my mother. Die Mütter warten. — The mothers are waiting. The surrounding words help you hear what changed.
Umlaut spelling is not universal vowel decoration
Some plurals add an umlaut, some add an ending, some do both and some do neither. Das Buch → die Bücher changes the vowel and adds -er; die Frage → die Fragen adds -n without an umlaut. Learn the plural with the noun instead of inventing a rule that puts dots everywhere.
In names and normal keyboard substitutions, ae, oe, ue often stand for ä, ö, ü. That does not mean every adjacent a and e in every German word is an umlaut. Follow the word’s actual spelling and pronunciation.
A two-minute practice task
Listen to schön, Tür and können. Repeat each once slowly, then inside a short phrase: sehr schön, die Tür, wir können. Finish by spelling schön correctly. The answer contains ö; schon is a different word. A small accurate contrast beats twenty approximate repetitions.