English-speaking children in German schools (Cologne)

Hello! I'm new to this forum, and I'm wondering if anyone can give me some information regarding placing English-speaking children in local German schools....We have 5 children (ages 11, 9, 8, 6, and 4), and we may be moving over there from the US later this year. We want our children to be bilingual, and international schools are not an option for us.