Use maximal capitals for the full titles of school and tertiary subjects:

English as a Second Language     Mathematics I     Modern History     Psychology 101

But the names of curriculum areas do not carry capitals:

English, mathematics, natural science and physical education are compulsory subjects in Australian high schools.

She is interested in history.

Similarly, use capitals for full formal titles of tertiary degrees and TAFE courses:

Bachelor of Applied Science     Master of Social Science     Doctor of Philosophy     Certificate III in Community Services     Diploma of Early Childhood Education and Care

But nonspecific references to courses have no capitals:

She completed a masters in science.     

The basic level required is certificate IV.

He received a doctorate.