In primary science, topics such as matter, air, water, and changes of state are generally introduced through hands-on activities using everyday resources. Many children find it difficult to understand basic science concepts such as states of matter (solids, liquids, and gases) and everyday phenomena such as evaporating and dissolving. Teachers may consider using the particle model to enhance conceptual understanding of phenomena observed in everyday life or encountered in hands-on activities. The teacher needs to decide when this approach is appropriate, in terms of content, context, and the ability of the children. Audio-visual aids (e.g. models, analogies, simulations) may be useful to supplement drawings of particles. Dynamic graphical presentation of change of state is effective in demonstrating the movement of particles and the attraction forces between particles. Explanation of some everyday phenomena or observations, for example dissolving, diffusion of perfume, movement of smoke, spread of powder or flowing water, in terms of particles can enhance children's conceptual understanding in science. (Contains 4 boxes.)