I'm having trouble deciding where to class an educational game: at 790.1 or at 371.337? 

Which number you choose depends on how serious the educational intent of the game is.  The usual clue to using 371.337 is some reference to the games being used in schools or by teachers. 

The best recourse when you have a quandary about terms that are applicable in two disciplines is to determine the interdisciplinary number from the index or from a note in an entry in the schedule for a number up the notational hierarchy from one of your numbers.  In this case, the answer is given in the index:

Educational games			790.1
	instructional use		371.337
	recreation		790.1

The number opposite the term itself is the interdisciplinary number.  That is almost always the "if in doubt" number and the "fall back" number (that is, the number to fall back on if there is no particular emphasis on any discipline).  Thus, in this case, if you have no good clue pointing to education, you class the game in recreation (790.1). 

Last revised: 31 January 2004