Here are some links that will help you with your revision.

Documents

year 5 learning objectives

 End of year Revision sheets

Web sites

This is the BBC bitesize website for Key Stage 2.  It is split into 3:-

Living things - biology (keeping healthy and life cycles)

Materials - chemistry units (states of matter / gases around us)

physical science - physics units (The Earth and beyond / sound)

http://www.bbc.co.uk/schools/ks2bitesize/science/

This web site might also be useful.  look down the list to find the topic you are after.

http://lgfl.skoool.co.uk/primary_science.aspx

Good luck.