This document covers a lesson on density. It begins by stating the lesson objectives of describing the three states of matter in terms of particles and their motion, describing what density is and ways to change it, and calculating density using a formula. It then provides diagrams and descriptions of particles in solids, liquids, and gases. It defines density as the amount of mass in a volume and provides examples of how to increase or decrease an object's density by changing its mass or volume. The document concludes by introducing the density formula of mass over volume and providing practice problems for students to calculate density and mass given various objects' dimensions and materials.