Smithers shows a clip about nuclear energy to the Springfield Elementary School during their plant field trip. The clip explains what nuclear energy is and describes the misconceptions associated with it.

How does nuclear energy work? Is radiation a risk? Find out the difference between nuclear fission and fusion, how uranium fuels the process, and the pros and cons of this alternative energy source.

Galileo explains to his student that, if two balls are dropped at the same height, they will both hit the ground at the same time, regardless of their weight.

Mr. Seaver begins teaching the class a lesson on gravity out of the textbook. He is especially confused by the book's claim that a coin and a feather will fall at exactly the same speed. After Luke challenges him to prove it, he tests the claim.

The students and Ms. Frizzle travel to Mercury, the first planet in our solar system, and learn that they weigh less because there is less gravity on the planet. They enjoy bouncing around with less gravity, and a few students take part in a contest to see who can jump higher.