"National Science Education Standards" (1996), published by the National Research Council, recommends that students learn to explain Moon phases and eclipses by the time they graduate from eighth grade. It is clear from the research literature, however, that misconceptions about Moon phases and eclipses are widespread and resistant to change, even among adults. In the most prevalent misconception, children and adults confuse the explanations for phases and eclipses by assuming that lunar phases occur when the Moon enters the Earth's shadow. The good news is that research studies have found approaches based on a constructivist view of learning to be very effective with students in grades five and above. While much research needs to be done, the studies reported here are fruitful in offering ideas for how teachers and curriculum developers can help students achieve the goals outlined in the "National Science Education Standards". (Contains 4 figures, 2 tables, and 2 notes.)