Inquiry-based instruction is common to nearly every model of gifted education. Six teachers of 14 secondary classes were briefly interviewed about their teaching and learning methods, use of inquiry-based strategies, classroom descriptions, a typical day, student expectations, and inquiry-instruction outcomes. A criterion-referenced checklist of 25 qualities of inquiry classrooms was used in a protocol analysis of the transcribed interviews. The classes were previously categorized as Most, Middle, and Least Inquiry with a modification of Llewellyn's simplified rubric for inquiry teaching complemented by teacher and student interviews and a teacher questionnaire. Extent of inquiry was well identified using only the teacher interviews and checklist. Teachers of Most Inquiry classrooms mentioned 21 or 25 of the 25 inquiry items. Middle Inquiry teachers mentioned 17 and 18 items. Least Inquiry teachers noted 6 and 9. Brief teacher interviews with a relatively straightforward coding system can assess the extent of classroom inquiry students experience.