Science Museum, London
Science Museum: Online Stuff: Big Clocks
Learn about the development of early clocks from the 14th through to the 19th centuries.
The Franklin Institute
The Franklin Institute: Clocks Teaching Time
This site from The Franklin Institute presents a number of activities, games, exhibits, scavenger hunts, resources, links related to clocks and telling time.
University of Cambridge
University of Cambridge: Nrich: How Many Times?
Sharpen your logic and digital clock-reading skills while working on this challenge. Solution available.