As the space between the molecules gets larger, the air takes up more space. This is why the heated balloon will expand during my experiments. How warm or cool something is. The students may need to know how a thermometer works. They also need to understand how the molecules move to make the water cool.
Dark colors heat better than lighter ones.
The sun's rays change energy to heat which makes the water warmer. Conductors and insulators need to be discussed. Same as above. Molecules expand with heat and contract with cold. Same as above.