For Ultrasound Module:
http://zapsurgery.org/zapsurgery/activities/sound.doc Can you see sound, or hear sound from an enclosed space? How fast does it go? These activities help your students explore such questions. (This link is to a Word document.)
For Cryosurgery Module:
http://web.physics.twsu.edu/facsme/nitro.htm A liquid nitrogen demonstration page, including links to information about safety, and number of fun activities involving tea kettles and ping pong balls.