Lesson Plans
Free, standards-aligned cryptography lessons for grades 3-12 — no account needed
Use Your CipherFidget
The main track: every lesson can be completed with your physical decoder ring
Learn the Ring
ROT-X: Basic Caesar Cipher
Send your first secret message! Learn the classic Caesar cipher by turning the decoder ring to a secret shift key.
ROT-X+: Rotating Shift Cipher
Level up: advance the ring one click after every letter so repeated letters stop leaking patterns.
Randomized Alphabet Ring
Swap the ordered alphabet for a scrambled one and turn 26 possible keys into 400 septillion.
Crack the Code
Known Plaintext Attack
If you can guess just one word of the message — "DEAR", a name, a date — you can unlock the whole cipher.
Frequency Analysis Attack
Become the codebreaker: count letters like Al-Kindi did 1,100 years ago and crack a cipher without knowing the key.
Digital Simulators
Advanced concepts using interactive digital tools
Morse Code & Encoding
Dots, dashes, and flashing lights! Learn the famous signal code — and why encoding a message is not the same as keeping it secret.
Binary & ASCII Basics
Discover how computers turn letters into numbers — and see that your decoder ring and a computer do the very same math.
One-Time Pad
The only cipher ever proven unbreakable — and the three strict rules that make or break it.
Enigma Machine Simplified
Rings within rings: how the WWII Enigma machine stacked rotating ciphers — and how Bletchley Park beat it.
More Lessons Coming Soon
We're developing additional lessons covering more advanced cryptography topics and future CipherFidget products.