The units on the ruler are in nanometers (nm). look at the graduations on the ruler. what does each graduation represent?

The units on the ruler are inches, centimeters, and millimeters. Nanometers (nm) is equivalent to 10^-9 m. Each graduation on the ruler represents 0.1 millimeters or 0.01 centimeters. The other side also has a graduation of 0.1 inch. The function of the ruler depends on how you use it. 

Ibelieve it's temperature! i'm not 100% sure.

Answerchemical;