This study examines how students in primary school (grades five and six) displayed creative thinking while working on an open-ended science project, and how they included science knowledge during the creative process. The findings show that students approached the creative process in six different ways: (1) by adaptation, (2) by transfer, (3) by synthesis, (4) by originality, (5) by practicality, and (6) by need. Students were able to make use of knowledge from the science domain while adapting throughout the creative process. Transfer of knowledge from other domains, synthesis of different types of ideas and knowledge, and originality were mostly used during the exploratory phase. Evaluating ideas based on their value according to the contextual factors of the project was also based on the approach's practicality and need. There was evidence to suggest that some students showed signs of higher order evaluative and creative thinking, based on the way they were able to combine different types of knowledge, make associations between, often remote ideas and knowledge, and make use of knowledge in new ways related to their level of knowledge and experience. The result shows that science education can focus on nurturing creativity without minimising subject knowledge in the process.