Possible Clues:

• #2s at college
• Graders, lecturers, and/or question-answering pros
• Tantalum symbols
• Jobs for some Ph.D. students
• Professors' helpers: Abbr
• Positions for Ph.D. students
• Some lab instructors, briefly
• Some exam graders, for short
• Helpers of profs
• Figures in some univ. classes