A new Junior Secondary Science Curriculum (JSSC) has been implemented in Hong Kong since September 2000. Developing pupils' problem-solving skills is one of the main aims of the new curriculum. This case study analyzes how teachers create environments to develop pupils' problem-solving skills through teaching a science theme entitled "The wonderful solvent—water" in Hong Kong junior secondary classrooms. Data were collected from classroom observation and post-lesson interviews. By demonstrating series of events that made up the entire learning experience of the students in classrooms, this article will illustrate how students carried out problem=solving processes, which include generating ideas, making interpretations and judgments, and using strategies to manage the complexity of situations. This study experiments are adopted in science lessons. Finding s also indicated that students are well motivated and their skills can be enhanced if decision-making authorities in designing setups, procedures and ways in solving scientific or technical problems have been devolved to them.