The February 2005 issue of The Science Teacher (TST) reminded everyone that by learning how scientists study stars, students gain an understanding of how science measures things that can not be set up in lab, either because they are too big, too far away, or happened in a very distant past. The authors of "How Far are the Stars?" show how the measurement of parallax permits scientists to infer astronomic distances (Murphy and Bell 2005). Students get the chance to make similar inferences through a free module available online at www.cavendishscience.org. Students begin by scaling sizes and distances, and end by creating models from which they calculate inferences that, in simplified form, give results that astronomers obtained similarly in recent times. The module begins with a series of (pencil and paper) scale-model constructions that illustrate the vast dimensions of objects and the space between them in the universe. The first model shows a pea-sized Earth, and subsequent model follows. The final job of the sequence is devoted to showing students how the events of the first few minutes of the universe--the so-called "big bang"--can be inferred from data presently available. A simplified model shows how the temperature of the universe at various times can be inferred from the speed of the expansion of the universe. The model neglects the fact that the material of the universe did not fly out at constant speed. This model does not suffice for an accurate calculation of the time of the big bang, but it does give students a glimpse of the way in which present day observations can be used to infer facts about the past.