Secret Code Machine
Use this machine to write in secret code. When you press a letter key, the dial will turn so that the arrow at the top points to that letter. The arrow on the inside will turn to point at the coded letter. If you send someone a message encoded this way, they can type the coded message in, and the original message will come out.
Try typing this encoded message in and see what comes out:
RXBR PZF VIWH VIJTFP VCNMDWXI
Use the green flag button to reset the machine.
The science of secret communication is called 'cryptography'. You can learn a lot about it here: http://en.wikipedia.org/wiki/Cryptography