It is quite common for people to believe that summer is warmer than winter,
basing the explanation on the belief that Earth is closer to the Sun during the
summer than in the winter. Even a sizable fraction of Harvard graduates carry
this belief (Schneps, 1987, mentioned in Green, 2003). In reality, this is exactly
opposite the situation in the northern hemisphere. The separation of Earth and
Sun is greatest at the beginning of July and least at the beginning of January.
More direct sunlight and the greater duration of daytime in summer months

The common plastic water bottle makes a useful container for demonstrating properties of gases and liquids. As typical examples, we know that "air" is a gas (made up of nitrogen, oxygen, water vapor, ozone, carbon dioxide, and several "trace" gases) and water is a liquid. We should also note that gases and liquids are both "fluids". That is, they can flow or change shape, rather than having a fixed shape like a solid.