Demonstrate and calculate the reasons for tidal bulges of water on both hemispheres of Earth, due to the Moon.

Why is it that we feel colder when the wind is blowing than when the wind is calm? What does it mean when the local weatherman gives the daily high along with the wind chill? How is the wind chill determined?

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.

This activity teaches how an ordinary ruler can measure (human reaction) time.

It's important to check the results from an experiment. Does the result make sense? Does it follow from other facts that are known? From the standpoint of teaching High School science, checking if one's results are sensible adds an additional layer of safety that the results are correct. (From the standpoint of advancements in Science, a basic research tenet is that results must be repeatable and not just a fluke.