Two booklets were developed by the Learning in Science Project (Primary)--LISP(P)--to help teachers adopt an approach to primary science teaching which would enhance children's understanding of floating and sinking. Both booklets were designed to enable teachers to reconceptualize their teaching task from activity-driven, didactic teaching to conceptual-change teaching. The first booklet was written for more confident teachers, using a less-structured approach, and the second for teachers who might prefer detailed guidance. Each booklet was evaluated during six 25-45 minute lessons over a 2-week period to determine the extent to which the authors of the booklets were able to convey their intentions to the teachers and to gain an idea of the problems encountered by teachers during the lessons. Data were obtained from student interviews and from a comparison of suggested strategies in the booklets and actual classroom practices. Findings (reported and discussed separately for each booklet) show that actions of the teachers matched the authors' intentions in some respects but departed from them in others and that use of the guide was influenced by the teachers' views of teaching and of how children learn. Implications of these and other findings for teaching science and for developing teaching guides are included. (JN)