The objective of this study was to investigate how classroom questioning and discussion skills, designed to increase scientific literacy and problem solving performance, affects student achievement in biology and chemistry. The two independent variables for this study were the effects of wait time and supportive intervention. The dependent variables used were the grades of students on the Biology and Chemistry Regents Examinations in the State of New York. Forty-four teachers from 15 suburban and rural high schools located in four central New York counties provided the data set. Each teacher designated one class as an experimental unit and provided them with instruction using the techniques of wait time and supportive intervention. Results varied between the chemistry and biology groups. Indications were that since biology instruction uses memorization, the effects of the independent variables were not significant. In chemistry, there was no difference in the grades of students in the classes of teachers who received supportive intervention. In biology, however, the students performed at significantly lower levels. Also in biology, the presence of "wait timers" made little difference in achievement, except with students in the highest ability group. Five tables and six figures are included. (TW)