I suggest a third table to make this a many to many relationship:
Location::LOCloc = LocationAssignments::LAloc
Interns::InternID = LocationAssignements::InternID
This will allow you to link an intern to as many locations as you need and a portal to LocationAssignments will list them all.
Here's a recently updated demo file on Many to Many relationships you can take apart and learn from: http://www.4shared.com/file/dZ0bjclw/ManyToManywDemoWExtras.html
Adding Date in and Date out fields to the third table would allow for keeping track by date too.
Exactly. Any data specific to a given assignment can be entered in fields defined in the LocationAssignments table.
This makes sense - thanks to all for your comments & the demo file. Now to put it to practice....