About every other undergraduate student eventually takes the UCLA elementary astronomy class Astronomy 3, and the two of us have been teaching about 1,000 of them every year. We will not repeat complaints about their poor and patchy high-school preparation in science, but we must mention it as an important phenomenon in U.S. education. The European system appears to be preferable, in which mathematics, chemistry, physics, and biology are mandatory and taught every year, although only 3 hours per week. It prevents large memory gaps and the spiral-wise parallel development in all four subjects makes it possible to teach on a higher level every subsequent year.