Year 11, these are the two useful links to help you revise for core science (the first link) and additional science (the second link).
You should complete at least one GCSE Science past paper a week in preparation to your exams in May and June 2017. The exam dates for core science are:
B1 16th May
C1 18th May
P1 24th May
The exam dates for additional science are:
B2 9th June
C2 14th June
P2 16th June