When supplying any type of feedback or evaluation it is important to do it on an individual basis, rather than to a group. Group feedback may be given to provide motivation and enthusiasm for the whole group's effort but individual feedback will give each intern/worker some concrete information on what you as an employer value and where you might see opportunities for the employee to make some additional improvements.

If you have an intern that isn't working out it's easier to discuss the problems (and solutions) if there was some form of job description or agreement made before the internship started. It's important to meet one on one with each intern to discuss performance issues and how they can improve and meet the goals and expectations of the employer. Oftentimes students are unaware of how their work behavior is perceived and a little guidance from their supervisor can put them on the right track and help them become a star performer within the organization.

I would recommend giving feedback individually because feedback is best served at an individual level where both the giver and receiver are actively participating in the process. This includes active listening, questioning and other communication methods to arrive at an understanding of what is being conveyed and where the opportunities for improvement are. A group feedback model is more appropriate if you are evaluating group or team performance or don't have as much time to spend with individuals.

If one is not working out, identify what the issues are, communicate this and how they can be improved upon. Then allow for a reasonable time for the intern to change or improve. Re-evaluate and then make a final determination whether you will be moving forward with this person or not. Be honest and professional and you will be doing them a service as well as your organization.

Best -

Michael Firth
Joined.com Host

I think it depends on the feedback. If we are discussing very general feedback, then a group discussion is just fine. That said, the more meaningful feedback tends to be facilitated 1on1. Interns, just like full time employees, are looking for constructive feedback on their performance as an individual.
If an intern isn't working out, does that mean that they will not be invited back for a full time position? Or will they be asked to leave their internship? In either case, I believe you need to be private about the discussion and direct to the individual on why they are not working out. Remember, the spirit of the internship is a two way street - the employer gets work done and the intern gets meaningful experience. Part of that meaningful experience is the honest feedback from a supervisor that their work did not meet expectations. That intern needs to know so as to improve for the next opportunity.
Good luck...
Best,
V