By IB do you mean international baccalaureate? I know some people who did that here in the US.
Yeah, looks like there's already more people on this forum that know about it than people who I've mentioned it to when they ask me 'what did you do in sixth form?', haha.
to create a entire new system from scratch for a client. We need to analysis the old system and what user wants. Design solution from the analysis. Create the system, test the system, document system( user manual, maintenance guide...) evaluate it...
I hate doing stuff like that. I think I had to do something similar in my first year of uni. Do you get to interview the client? Once you find what problems the old system has and find out what the client wants, it's just about learning how to make it.
If you want big marks, I wouldn't worry all that much about how amazing you actual build is or isn't, just concentrate on including absolutely everything in your report/guides/whatever, and follow the marking criteria like a mad man. If you make an effort to fix what they want fixing, then you'll be fine.