My DS did Greece his 1st semester freshman year, he had a blast, but the courses were light, when he got back for spring semester the hammer dropped swifty and hard, he had make up and take two AFROTC classes, two engineering cornerstone project classes, calc & physics II plus technical writing and he had to travel to a crosstown university 3-4x a week for ROTC, he was basically roadkill after the semester, then had to take calc III and statics for the summer session to stay on his degree track. It was very nice the AF paid for his semester in Greece, but he was not prepared for the academic tsunami when he got back. Moral of the story, study aboard is a great experience, but be prepared to make up a ton of work.