1. **State the problem:** We need to find the scale used to create the map of the school, given that the distance on the map between two classrooms is 4.5 cm and the actual distance is 18 feet. 2. **Formula and concept:** The scale of a map is the ratio of a distance on the map to the corresponding actual distance. It can be written as: $$\text{Scale} = \frac{\text{Distance on map}}{\text{Actual distance}}$$ 3. **Calculate the scale:** Substitute the given values: $$\text{Scale} = \frac{4.5 \text{ cm}}{18 \text{ ft}}$$ 4. **Simplify the fraction:** $$\frac{4.5}{18} = \frac{\cancel{4.5}}{\cancel{18}} = \frac{1}{4}$$ 5. **Interpret the scale:** This means 1 cm on the map represents 4 feet in reality. 6. **Answer:** On the map of the school, 1 centimeter represents 4 feet.