CK-12 Foundation
Ck 12: Radioactive Half Life
[Free Registration/Login may be required to access all resource tools.] Explains radioactive half-life and radioactive dating, and demonstrates how to solve problems with each.
Physics Aviary
Physics Aviary: Practice Problems: Decay Constant and Half Life From Table
Determine the decay constant and half-life of an isotope based on the activity data of the isotope as a function of time.