I'm all in favour of project-based learning in Computing -- if the project centres on a genuine problem to be solved, and the pupils are given plenty of time to solve it. I used to allow them 6 weeks. But that's a long time for kids who are more used to a much more structured set of lessons, so I used to build up over time, using micro and mini projects.
A micro project is where you set a problem, and give the kids one lesson in which to solve it. That's not much time, so you may have to do some of the organising for them. For instance, you may need to say who is going to do what in each small group, rather than allow them to take 20 minutes to argue it out between them.
cross-posted at www.ictineducation.org
Terry Freedman is an independent educational ICT consultant with over 35 years of experience in education. He publishes the ICT in Education website and the newsletter “Digital Education."