Lato (summer in Polish) is a free, open-source font designed by Łukasz Dziedzic. 

“When working on Lato, Łukasz tried to carefully balance some potentially conflicting priorities. He wanted to create a typeface that would seem quite “transparent” when used in body text but would display some original traits when used in larger sizes. He used classical proportions (particularly visible in the uppercase) to give the letterforms familiar harmony and elegance. At the same time, he created a sleek san-serif look, which makes evident the fact that Lato was designed in 2010 — even though it does not follow any current trend.” -tyPoland

This font is truly beautiful and versatile. I’ve used it on several projects lately, and it’s garnered a fair amount of attention. It’s great for students because it’s a well-designed, comes in a large variety of weights, and it’s free! 

The entire Roman font family is available for free download through Google web fonts.