C.P. 12
Note: This is a newer version the what we are using at school. Projects created in the Community Edition will not open in ours school's version. However, you can open your school projects in the community edition of the software.
This book is full of hands on activities to help demonstrate how computers work. While it is geared towards young children, it is a good resource for those interested.
This is a pretty cool cipher that took over 300 years to crack, and even now it is still formidable. Take a look at how it works, and try encrypting your own message with this cipher. Have fun!