Unlike external body parts, organs are invisible and untouchable, making it difficult for children to learn their size, position, and function. With the advent of low-cost sensing, ubiquitous computation, and emerging e-textiles, new teaching approaches are developing that link the physical and virtual worlds. In this thesis, I report on the design and evaluation of several wearable e-textile prototypes --called BodyVis--that combine embedded sensing and interactive visualization to reveal otherwise "invisible" parts and functions of the human body. Key findings from an open-ended cooperative inquiry design session with children were used as guidelines in developing the first prototype. Versions of the second prototype were developed before and after a second cooperative inquiry design session. The final prototype was then evaluated through three design evaluation sessions. Three examples of use demonstrate the potential of BodyVis to engage, excite, and pique children's curiosity in learning about the human body.