Doing science as explorers, students observe, wonder and question the unknown, stretching their experience. To engage students as explorers depends on their safety in expressing uncertainty and taking risks. I create these conditions in my university seminar by employing critical exploration in the classroom, a pedagogy developed by Eleanor Duckworth, based on Jean Piaget and Bärbel Inhelder. My students observe nature and evolve trust in working together. They experience historical resonances through constructing their own diagrams and proofs of Euclid's geometry and experimenting with motions in response to Galileo's 1632 "Dialogue." Historical figures become virtual members in the classroom, whose historical discourse is treated as if written by a current collaborator. Finding parallels between their thinking and history, students invent such instrumental assists as modeling moonrise through configurations of their bodies, balls and a lamp in the darkroom, which they later test observationally. In the process, their curiosity becomes self-sustaining, instigating further investigation. Drawing on diverse strengths of participants, collaboration among explorers is not like a chain; it can be "as strong as its strongest link." One person's insightful confusion can take the whole group's understanding to a new and different place; an experiment or diagram beginning in one person's hands soon engages all. Their collaboration has at its disposal the union of life experiences of its members. As students generate multiple concurrent, conflicting perspectives, they diverge from the goal-directed curricula of most schools today. They learn how to observe; how to question; how to communicate; how to determine what is reasonable and what is not; how to create knowledge rather than just accepting it.