This study was designed to investigate (a) the feasibility of modifying an existing question classification scheme for use in measuring the inquiry level of teachers' questions and (b) the relationship between the inquiry level of teacher questioning and student achievement. Data for the study were collected from three specific classroom discussions taking place in 40 ninth grade earth science classes. Conclusions included the following: the categories of Smith and Meux's classification scheme can be categorized into those demanding a low or high amount of inquiry (as defined by the investigator); the investigator was able to reliably observe the inquiry level of teacher questioning through the use of the modified Smith and Meux question classification scheme; the student's achievement on the posttest was significantly affected by the teacher's inquiry level as determined by the teacher's questions. (Author/PR)