Research studies in science education have revealed that wait-time, the duration of teacher and student pauses in questioning dialogue, is an important variable in teaching. In this study, discussion materials were gathered, from 4 groups of 10 teachers, each week for a semester. The groups were defined as: (1) comparison group; (2) instruction in effective questioning group; (3) wait-time feedback group; and (4) instruction and wait-time feedback group. Discriminant function analysis and analyses of variance revealed that the wait-time feedback groups experienced greatest increases in wait-time and exhibited higher cognitive levels of interaction in classroom discussions. Longer student answers and more student talk were also found in the wait-time feedback groups. Re-analysis of the data separated the feedback groups into three categories: (1) those who maintained pauses of three seconds or more in several discussion sessions; (2) those who reached the three second criterion at least once in a discussion; and (3) those who were unable or unwilling to pause to the criterion. Significant differences favoring the effective wait-time group were found in the following areas: fewer memory-level, rhetorical, management, and leading questions; smaller percentage of teacher talk in discussions; and longer student answers. Eleven tables are included. (Author/JMK)