Junior Year Requirements Solution

Where a grouping has more than one puzzle, those puzzles have the same answer (submitted by different teams, since there were more teams than answers).

Each answer is a single word, and when they are grouped into phrases of one to three words in the order given, they form the titles of either real MIT classes or ones from the first two years of this Mystery Hunt. This was a little harder than it might have been because some of the names were shared by classes in other departments. When you found the right classes, take the department/course number as an index into the alphabet to spell the answer, COURSES.
Grouping
 Answer
 Class Number
 Course
 Letter
A) 4.666, 19.012 INDUSTRIAL
 3.932 (MIT)
 3
 C
B) 19.13, 19.678 PRACTICE
C) 7.270, 19.456 HEALTH
 15.136J (MIT)
(also 10.547J, HST920J)
 15
 O
D) 19.345, 6.551J TECHNOLOGY
E) 18.000, 19.234 DOWNTOWN
 21H.234J
(also 11.339, 11.026J)
 21
 U
F) 19.00s QUANTUM
 18.737 (MIT)
 18
 R
G) 19.789 GROUPS
H) 24.917, 18.123 DECODING
 19.1289 (MH)
 19
 S
I) 5.198, L.??? ADVANCED
J) 19.567 CRYPTOGRAPHY
K) 19.001, 18.101 ARCHAEOLOGICAL
 5.24J (MIT)
(also 3.985J)
 5
 E
L) 24.845 SCIENCE
M) 19.2837 WEB
 19.2352 (MH)
 19
 S
N) 19.503 WORD
O) 6.1835 PUZZLES