Possible Clues:

• Pre-college, to textbook publishers
• Like some textbook publ.
• Educ. publishing division
• Pertaining to most students
• 1-to-12, gradewise
• Like a twelve-grade school
• Type of textbook market
• Of grades 1 to 12, for short
• Grades 1 to 12, briefly
• Appropriate for kids K-12