Simple
- (1) Lock them inside a room + Free Oxygen.
- (2) Give them a PC with Internet connection + IDE of choice + access to Food.
- (3) Have wireshark or similar method of logging all inbound and outbound traffic.
- (4) Give him a medium assignment.
- (5) Examine all HTTP traffic, post assignment completion.
- (6) If subject has copied large chunks of source code, terminate Subject.....
Edit:
As makerofthings7 as pointed out, in practical terms one could do a video capture (screen capture).