Abstract
When starting German 6th grade, students already have broad prior experiences with
decimal fractions as numbers for measuring quantities. Diagnostic written tests and
individual interviews were used to examine how far this experience promotes the transition
to abstract decimal fractions shortly before they are taught systematically. Results showed
that this transition is still only just beginning in many students, and that the necessary
extension of the place-value system is still hampered by incorrect transfers from natural
numbers.