The passive is used in German to describe either actions/activities ("Passiv mit werden") or results/states ("Passiv mit sein"). In these passive exercises, you must rewrite the active sentences to passive. The exercises are suitable for level A2.2/B1 - Have fun practicing!
Online Passive Exercises in German - Das Passiv
Short rule:
Passiv mit werden: werden + Partizip II (Die Tür wird geöffnet.)
Passiv mit sein: sein + Partizip II (Die Tür ist geöffnet.)
More Informations about passive in German