Field trips to the Michigan 4-H Children's Garden must provide rich science learning experiences for students and teachers. A key to this is getting students to ask questions. To facilitate student question asking we developed the Wonder Wall, a "wall" where students could write their questions. Student questions were answered as part of the field trip and written answers were provided following the field trip. Nearly 75% of the 455 2nd and 3rd grade students in this study posted questions. Questions were both basic information (50%) and wonderment (50%). Basic information questions were simple questions that focused on the garden, plants, staff, and field trip activities. Wonderment questions were more complex questions that focused on field trip learning activities. The 50% wonderment questions was greater than expected, suggesting that students posted these questions after carefully thinking about what they had learned. Student questions provided a real-time assessment of student understanding and interests. Wonderment questions could easily be extended into an experiment, giving students the opportunity to direct their own learning. The Wonder Wall is a simple, easily integrated tool that engaged students in asking questions. It provided educators with valuable insights into student understanding and interests. The Wonder Wall was a powerful part of our field trips and we recommend incorporating it into field trips where ever possible. (Contains 4 tables and 1 figure.)