Unfortunately, not all the German verbs follow the regular pattern shown in the previous lesson; there are some verbs with slight variations in their stem. These verbs are called 'Irregular Verbs'.

1. Stem ending with 'd' or 't':

As it would be difficult to pronounce the 'st' ending for 'du' and the 't' ending for 'er/sie/es' & 'ihr', an 'e' is placed before the ending of these verbs.
The extra 'e' is added only to the 'du''er/sie/es', and 'ihr' verb forms, other verb forms aren't affected.

See more:

Pronoun finden leiden
du findest leidest
er/sie/es findet leidet
ihr findet leidet

2. Stem ending with 's', 'ss', 'ß', 'x', 'z', or 'tz':

If the verb stem ends with any of the following endings, then the 'du' verb ending becomes a 't' instead of 'st'.
Only the 'du' verb form is affected.

See more:

Pronoun genesen küssen heißen sitzen
du genest küsst heißt sitzt

3. Verbs with a vowel change

Some verbs have the vowel in their stem change with the 'du' and 'er/sie/es' form of the verb. These verbs are best learnt by heart.
The three most common vowel change patterns are:

  • a to ä
Pronoun backen fahren schlafen waschen
du bäckst fährst schläfst wäschst
er/sie/es bäckt fährt schläft wäscht
  • e to i
Pronoun essen geben sprechen brechen
du isst gibst sprichst brichst
er/sie/es isst gibt spricht bricht
  • e to ie
Pronoun befehlen lesen sehen stehlen
du befiehlst liest siehst stiehlst
er/sie/es befiehlt liest sieht stiehlt

This concludes our lesson, quite simple, eh ?
Make sure to check the grammar table associated with this lesson, it contains most of the irregular verbs that appear within the German language.