Dear Tom,
There are always many problems in teamwork, although it is regarded as the most efficient way. Your case can be seen as a quite common one, known as "free rider". It refers to people who don't complete their work in a team. Under this circumstance, you and other teammates need to communicate with that student. Try to encourage him. Give him some reward. Or you can also put some pressure on him. I believe this problems can be handled well if you talk to him sincerely.
yours
Mary