There is sex education at every school, details can be found in the BW Schools Act. http://www.landesrecht-bw.de/jportal/?quelle=jlink&query=VVBW-2206-KM-20010512-SF&psml=bsbawueprod.psml&max=true
The legal guardians have to be informed about goals, contents and forms of sex education in a timely manner.