WORD SPIRAL

Starting from 1, fill in the grid clockwise with four-letter words. The last letter of each word becomes the first letter of the next to reveal an educational term. 1. Clenched hand 2. Burial vault 3. Policeman's route 4. Skinny 5. Naming word 6. Unfeeling 7. Preference 8. Not fast 9. Lacking strength 10. Pottery oven 11. Requirement 12. Daybreak 13. Pistachios, say 14. Prophet 15. Genuine 16. Praise, extol