Prior to a curriculum unit on European exploration of the New World, a class of fifth grade U.S. history students stated what they knew (or thought was true) about the discovery of America and what they wanted to learn about it. After the unit, they reported what they had learned about the general topic of European exploration of North America. In addition, a stratified sample of 10 students was interviewed concerning the details of their thinking about several key subtopics. Prior to the unit, half of the students knew something about Columbus but little about European exploration of the New World. During the unit, the students developed considerable knowledge about the Vikings as precursors of Columbus, Columbus' life and travels, Ponce de Leon and other New World explorers, the origin of the name "America," and the rivalry among England, France, and Spain in establishing land claims and colonies in the New World. Most students developed an understanding of the motives and goals of explorers and the monarchs who commissioned their voyages, but they had a difficult time placing these voyages within a larger perspective. They also expressed numerous naive misconceptions. Use of newly developed curriculum guidelines and instructional materials for teaching about the Encounter should help improve traditional instruction on the topic. (Contains 22 references.) (Author/LBG)