This document defines and explains the key properties of matter: mass, volume, density. It states that matter is everything around us and has general properties like mass and volume shared by all, as well as specific properties that differ between types of matter like color and hardness. Mass is defined as the amount of matter in an object and is measured in kilograms or grams using scales. Volume is the space an object occupies and is measured in liters or milliliters using measuring cylinders, with formulas used for solids. Density refers to the concentration of matter in a volume and is calculated by dividing mass by volume.