Phil conducts an experiment in which he tries to spin a pencil on its tip. He fails initially but is successful after sticking it through a circle of cardboard. He explains why it works and mentions the "smart" way to describe the phenomenom: the conservation of angular momentum.

Bill Nye show us how a circuit works by comparing electrons to water.

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.

A series of simple machines help collect mushrooms and crush them to produce a drink for Dr. Robotnik.

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.