Phase Changes
Phase Changes is what happens when matter shifts between solid, liquid, and gas, like ice melting into water.
Think of it this way
An ice cube on a warm plate melts into a puddle of water. If you boil that water on the stove, it turns into steam that rises into the air. The same H2O moved from solid to liquid to gas just by adding heat. Take the heat away and the changes reverse — steam condenses, water freezes back to ice.
Explaining phase changes by grade level
Think about an ice cube sitting on a warm plate. It starts hard and cold, then slowly turns into a puddle of water. The ice did not disappear. It changed form. Heat from the plate made the ice soften and flow. If you put that water in a freezer, it turns back into ice again.