Strong Verbs in German

Strong verbs (starke Verben) in German are irregular verbs that change their stem vowel (called Ablaut) when conjugated in the past tense (Präteritum) and the past participle (Partizip II). For example, the verb "singen" (to sing) shifts to "sang" (sang) and "gesungen" (sung). Unlike weak verbs, strong past participles typically end in "-en" instead of "-t". German learners usually study these verbs in groups representing their vowel change patterns (e.g., i-a-u, ei-i-i).