Instructors themselves must decide how to grade students who are drafted before final exams, several department heads agreed yesterday.

The lecturer in each course will choose whether hour exams, papers, lab reports, or even classroom response will be the basis for marks under the new "cumulative credit" plan.

On Tuesday the faculty passed the new credit system, under which a student gets partial credit for courses if he is called to service in the middle of a term.

New Plane Possible

Arthur Smithies, chairman of the Department of Economics, said last night that--in the large basic courses--"the lecturer, and not the section man, will make the decision as to suitable evidence of the quality of the student's work" He added that the faculty would quickly consider new plans if the draft hit the College hard.

All department spokesmen said they expected no immediate loss. "No one seriously believes it will affect any department," said Erwin B. Newman, chairman of the Department of Psychology. "We plan to take each case as it comes. With freshmen it may mean individual exams."