In this unit, students explore how solids and liquids can change by heating, cooling, building up, carving, and taking apart. They investigate several properties of solids and liquids including color, shape, and hardness. They learn through a text that hard materials can be carved and soft materials can be built up. They build a sculpture and take it apart to make another sculpture with different properties (this leads into a later understanding of particles). They compare the properties of several liquids and solids and argue from evidence for whether sand is a solid or a liquid. They use what they have learned about solids and liquids to test different materials for a cold pack.