LPT: When giving feedback to young interns or co-ops, use the phrase "early in your career" instead of "you are young".

By doing so not only will you avoid legal issues around age discrimination at work, but also make sure they are motivated properly and stay grounded. Fresh out of college Interns need to understand that early in their career, they need to work harder, observe much and learn by doing. By calling them young disincentivizes them from realizing that their youth is their actual strength.