PBS
Pbs Learning Media: Sesame Street: Sink or Float Educator Guide
This is an educator's guide for a unit on things that sink or float. It includes lesson plans, experiments, and activities. Students apply the scientific method as they investigate whether objects sink or float.
Center of Science and Industry
Cosi Columbus: Buoyant Bubble [Pdf]
Learn about density in this hands-on science experiment. Includes full list of materials, procedures, and scientific explanation of what makes an object float or sink. [PDF]