Good entries come from teams that work well together and take full advantage of every member's talents. Dividing up tasks is fine, but everyone's contribution should significantly benefit the team and its entry. If possible, allow students to form teams themselves. They will be more likely to help one another without complaint, and less likely to resort to fighting in times of stress. Address a widespread problem.
Good entries tackle problems with an observable impact on a large segment of the community.
The problem should stem from a recurring phenomenon that has not yet been effectively resolved, rather than an isolated incident. If the students have a vested interest in the problem, they will understand it better and be more eager to find an innovative solution. Propose a feasible solution. Good entries present solutions that are not only creative and original, but also realistic and achievable within the scope of the award. Real-world testing, using appropriate sampling methods, will let your students know if their solution is workable.