Misha thinks that hot water Dan dissolve more sugar than cold water. To test this, Misha fills three breakers with water. One breaker Is kept at room temperature, the second beaker is heated on a burner, and the third beaker is refrigerated for one hour. misha then adds the same amount of sugar to each breaker, stirs 10 times, filters out the remaining solid sugar, and records the mass of sugar left undissolved in each breaker. How can misha improve the validity of the results?