Annette, I'll make two points that are relevant to your question: (1) To keep students engaged in learning and excited about science, we should present science not as facts to be memorized but as a process of exploration and discovery. (2) There is now a substantial body of research on how children learn and how they learn science best. The most positive outcomes occur when inquiry-based pedagogical methods are used in the classroom. I'm sure others will suggest various resources for this. I am a strong proponent of the Phenomenon-Based Learning (PBL) approach, which is ideal for eliciting the kind of creative curiosity that makes students want to learn. It builds knowledge of, and interest in, science as a result of observations of real-world phenomena, or perhaps some interesting toys, gadgets, et cetera. The idea is to teach broader concepts and useful thinking and performance skills rather than asking students to simply memorize facts. (Memorizing facts is not science.) What happens is, students, working in groups, will investigate an interesting phenomenon, discuss it with each other, and, motivated by their own curiosity, explore and discover how it works and what sorts of science are involved. So the approach to learning is based on reasoning, curiosity, and creativity.