LibCryptooo is an extension of basic cryptography for schools.
Caution: in the current version, menus and dialogs are only available in French. Frequency analysis is related to a French text.
Some historical methods of encryption are available: substitution, Caesar, linear function, Vigenère, transposition.
The encrypted text can be studied by analysis of frequency and be decrypted.
With this extension, you will find a folder containing some examples of actual use in the classroom.