Some solids are not very hard. Butter is a soft material. Adam takes the butter out of the fridge and puts it into a warm room. What happens to the butter? The butter in the warm room is ______.

You have learned a lot about different materials. But materials are not just solid things. Liquids like water are also materials. Gasses like air are also materials. You can divide up materials into solids, liquids and gasses. But water can change from one to the other. Water freezes to make ice. Water boils to make steam.