Groups of children at a science museum were pre- and post-assessed with a type of concept map, known as personal meaning maps, to determine what new understandings, if any, they were gaining from participation in a series of structured hands-on activities about bones and the process of bones healing. Close examination was made regarding whether children's prior knowledge or a ceiling effect was influencing results. Children made significant gains in vocabulary and concepts related to both bones and the bone healing process. Many children also demonstrated that their comprehension moved from a novice level to a transitional level of understanding. Prior to participation, children were more uniformly unacquainted with ideas about the healing process of bones than they were about bones; this led to more consistent learning gains related to the healing process. There was some indication of a ceiling effect occurring when children revealed what they had learned about bones, but not when they revealed what they had learned about the bone healing process. Although the prior knowledge theory was not statistically supported, data did show that children with greater understanding prior to the Busy Bones Lab activities end up with correspondingly greater understanding. This suggests that addressing concepts related to bones prior to a lab experience may bring more children to a higher level of understanding before engaging in the lab experience.