A method for the construction of a Galilean thermometer out of common chemistry glassware is described. Students in a first-semester physical chemistry (thermodynamics) class can construct the Galilean thermometer as an investigation of the thermal expansivity of liquids and the temperature dependence of density. This is an excellent first laboratory for physical chemistry as it generates student interest; plus, it is a green experiment only using water, food coloring, and glassware that can be recycled from year to year. The thermometer can also be constructed without a detailed discussion of the mathematics behind it, making it accessible to general chemistry students. (Contains 2 figures.)