You also already know the irregular verbs. When you learned the present perfect tense, you learned that the past participle of irregular verbs ends in -en and that there is often a vowel change in the verb root.

The root vowel of these verbs also changes in the simple past:

schreiben: Johann Wolfgang Goethe schrieb viele Gedichte und Theaterstücke.

Unlike regular verbs, with irregular verbs, there is no -(e)te- inserted between the root and the personal ending. In the first- and third-person singular, there is no personal ending.

The verb is conjugated like this:

Be aware that the verb root of irregular verbs in the simple past and in the past participle can be the same, but are often different: schreiben – schrieb – geschrieben, but: finden – fand – gefunden. These so-called root forms have to be memorized for each irregular verb.

In a few cases, one or more consonants may also change:

kommen: Nach seiner Italienreise kam Goethe 1778 zurück nach Weimar.

gehen: Goethe ging gerne spazieren, weil er sich für die Natur interessierte.

essen: Goethe liebte gutes Essen und aß gerne Fleisch.