4 ideas
Tsiolkovsky's 1893 tale has the narrator and a physicist friend wake up inside their house, which has somehow been moved to the Moon. They test the place like a laboratory: jumping several metres high, carrying loads that feel six times lighter, watching a pendulum swing slowly, and finding that they cannot hear each other or make a flame burn. Only at the end is it revealed to be a fever dream.
On the Moon gravity is about one sixth of Earth's, so weight drops but mass and inertia stay the same. A man can lift and leap far more, yet he still has to push hard to start or stop a heavy object moving. Falls and pendulum swings are slower, so a person's sense of time and their motor habits no longer match what is happening around them.
With no atmosphere, sound can travel only through solid contact, so the men hear nothing across open space. There is no convection or scattered light: the sky is black even in daylight, shadows are pitch-dark and sharp-edged, and sunlit surfaces burn while shaded ones freeze. Without air, liquids boil away and fire cannot burn.
Physical constants become intuitive when you imagine a body experiencing them, step by step, rather than stating them as numbers. Framing the Moon as a place two people must walk, speak, eat and sleep in makes the reader test every everyday assumption.