Early in their chemistry education, students learn to do empirical formula calculations by rote without an understanding of the historical context behind them or the reason why their calculations work. In these activities, students use paperclip "atoms", construct a series of simple compounds representing real molecules, and discover, just as early chemists knew, that only the empirical formulas could be found from their experimental results even though they do not know the masses of the atoms. These activities, designed for high school or college introductory chemistry, take about 150 min to complete.