Rocket lays the board on a stack of two books. Raven stretches a tape measure along the floor.
"Rise is the height of the books," Rocket says. "Run is how far along the floor. Rise over run."
Raven reads. "At 40 centimeters along, the board is 10 centimeters up. At 80, it is 20 up."
"Ten over forty is one quarter," Rocket says. "Twenty over eighty is one quarter. What do you notice?"
"The same slope anywhere on the board," Raven says. "A ramp is a line."
Nova hovers by the stack, her light on the top book. "Add a book," she says. "Predict first."
"Steeper. A bigger slope," Rocket says, already reaching for a book. Nova hums. "Measure, then tell me the number."
Build a ramp from a board on books. Measure its rise and run at two or three places, and show the slope is the same.
Then add a book and measure again. A steeper ramp should give a bigger slope.
These are the crew's own measurements from the Puzzle Post floor, in centimeters.
| Run (cm) | Rise (cm) | Rise ÷ run |
|---|---|---|
| 40 | 10 | 0.25 |
| 80 | 20 | 0.25 |
| 120 | 30 | 0.25 |
Every row gives the same slope, 0.25. The ramp is a line, so rise over run matches anywhere along it.
With a third book, the crew measured a rise of 12 cm at a run of 40 cm. Slope 0.3: steeper.
A ramp is a line, and its slope is one number. Tomorrow a race with a head start brings in the y-intercept.