Secret Code Cipher Wheel
Project Overview:
Build a spinning cipher wheel that lets you write and crack secret coded messages, just like real cryptographers do! This project uses math to scramble letters into a code, showing how the same basic idea keeps everything from text messages to online banking secure!
Materials:
2 Paper Plates or Circles of Cardstock (different sizes)
A Marker
A Ruler
Scissors
A Brass Fastener (paper brad)
A Pen and Paper (for writing messages)
Instructions:
Cut your two circles so one is noticeably smaller than the other — the small one will sit on top of the big one.
Divide the outer edge of the large circle into 26 equal sections using your ruler, then write one letter of the alphabet in each section, going in order (A, B, C...).
Do the same on the smaller circle: divide it into 26 equal sections and write the alphabet around its edge too.
Poke a small hole through the center of both circles and attach them together with the brass fastener, so the small circle can spin freely on top of the big one.
Pick a "shift number," like 3, and rotate the inner wheel so its letter "A" lines up with the letter "D" (3 spots ahead) on the outer wheel.
To encode a message, find each letter of your message on the outer wheel and write down whatever letter lines up with it on the inner wheel.
Give your coded message and your shift number to a friend, and have them build their own wheel to decode it.
Try a few different shift numbers and see how the coded message changes each time.
Explanation:
This type of code is called a shift cipher because every letter gets bumped the same number of spots down the alphabet based on a number you picked in advance. Since you and your friend both know that number, decoding is easy—they just spin their wheel to match and slide everything back to reveal the real message. However, for a person who doesn't know the shift number must guess 25 different possibilities before they'd ever crack it, which is really what turns this into an actual code instead of just scrambled letters. And believe it or not, the encryption protecting your passwords and credit card info online runs on this same basic idea—just with way more complicated math and millions of possible combinations instead of 25!
