Pursuing a STEM degree — which stands for science, technology, engineering or mathematics— has historically paid off well for college students. But earning that credential may require a lot of study time.

Many of the 10 colleges where students spend the most time studying have STEM-focused curriculums, according to The Princeton Review’s most recent rankings.

The publication surveyed students at nearly 400 U.S. colleges and asked how many hours they spend studying outside of class. Students at California Institute of Technology reported the most study time, followed by Harvey Mudd college.

All Caltech students — including English and history majors — complete a STEM-focused core curriculum, according to the school’s website. And notably, the curriculum is “extraordinarily” hard, the college says. Harvey Mudd exclusively offers Bachelor of Science degrees in a variety of STEM fields to its undergraduates.

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