Speaking of NOVA, this web offering is the companion site to an episode of the series called “Decoding Nazi Secrets,” a two-hour special that chronicled how the Allies succeeded in cracking the infamous German message-coding machine, the Enigma. Students can learn some of the tricks that codebreakers use to solve ciphers, then use their new-found talents to make sense of sample coded messages. They can also manipulate an online version of an Enigma-like machine to encode their own messages, then eMail the messages to friends with instructions on how to decode them using a secret key. The site also details how the Enigma works, takes visitors behind the scenes of the Allied codebreakers who cracked the Enigma, and features a discussion of a modern-day application of cyphers: the encryption that is intended to make web transactions safe. A Teacher’s Guide includes suggestions for using the site (and the episode) in the classroom.