Question 1

What is present-tense stem-vowel change?

Accepted Answer

Some German strong verbs change their stem vowel only in the du and er/sie/es forms of the present tense: a → ä (fahren → du fährst), e → i (sprechen → du sprichst), or e → ie (sehen → du siehst). Every other person (ich, wir, ihr, sie/Sie) conjugates normally, with no vowel change.

Question 2

How does this relate to a verb's Partizip II and Präteritum?

Accepted Answer

It's an independent, third quirk of the same strong verb: helfen, for example, is irregular in both Präteritum (half) and Partizip II (geholfen), and on top of that changes its stem vowel in the present tense (du hilfst). Three separate things about the same word - knowing one form doesn't guarantee knowing the others, so each is worth drilling on its own.

Question 3

Do all strong verbs change their stem vowel in the present tense?

Accepted Answer

No. Many strong verbs (schreiben, verlieren, scheinen, for example) are only irregular in the Präteritum and Partizip II, and conjugate completely predictably in the present tense. Present-tense stem-vowel change is a separate group that only partly overlaps with the general list of strong verbs.

Question 4

What's the fastest way to learn these forms?

Accepted Answer

The most effective way is to drill the form inside a real sentence with a clear subject, rather than memorizing a bare list. The free Telegram bot Immer wiederholen does exactly that with spaced repetition.

Infinitiv	du	er/sie/es	Change	English
befehlen	befiehlst	befiehlt	e → ie	to command
brechen	brichst	bricht	e → i	to break
erschrecken	erschrickst	erschrickt	e → i	to be startled
essen	isst	isst	e → i	to eat
fahren	fährst	fährt	a → ä	to drive, to go
fallen	fällst	fällt	a → ä	to fall
fangen	fängst	fängt	a → ä	to catch
geben	gibst	gibt	e → i	to give
graben	gräbst	gräbt	a → ä	to dig
helfen	hilfst	hilft	e → i	to help
lassen	lässt	lässt	a → ä	to leave, to let
laufen	läufst	läuft	au → äu	to run
lesen	liest	liest	e → ie	to read
nehmen	nimmst	nimmt	e → i	to take
raten	rätst	rät	a → ä	to advise
schlafen	schläfst	schläft	a → ä	to sleep
schlagen	schlägst	schlägt	a → ä	to hit
sehen	siehst	sieht	e → ie	to see
sprechen	sprichst	spricht	e → i	to speak
sterben	stirbst	stirbt	e → i	to die
stoßen	stößt	stößt	o → ö	to push
treffen	triffst	trifft	e → i	to meet
treten	trittst	tritt	e → i	to step
vergessen	vergisst	vergisst	e → i	to forget
wachsen	wächst	wächst	a → ä	to grow
waschen	wäschst	wäscht	a → ä	to wash
werfen	wirfst	wirft	e → i	to throw

German present-tense stem-vowel change verbs

Table of forms

How to actually learn these

Practice these forms in the bot