Substitution Cipher Cryptogram Worksheet
Swap every letter using a fixed secret key
- Grades 5–9
- 25 minutes
- Intermediate
- 8 exercises
- Answer key included
A substitution cipher swaps every letter for a different fixed letter — unlike Caesar (a single shift) or A1Z26 (letters to numbers), each letter has its own unique replacement. This worksheet gives students a complete key and a set of encode and decode challenges, building toward the frequency-analysis skills real cryptographers use. Print the student PDF and answer key below, or work through the exercises on this page.
Printable PDF — free to download & print
How to use this worksheet
A substitution cipher replaces each letter with a different fixed letter. Use this key to encode and decode: A=Q B=W C=E D=R E=T F=Y G=U H=I I=O J=P K=A L=S M=D N=F O=G P=H Q=J R=K S=L T=Z U=X V=C W=V X=B Y=N Z=M. Encode by looking up each letter; decode by working the key backwards.
Exercises
- 1. Encode with the key: CAT
- 2. Encode with the key: DOG
- 3. Encode with the key: HELLO
- 4. Encode with the key: SECRET
- 5. Decode with the key: LHN
- 6. Decode with the key: EGRT
- 7. Decode with the key: WKQOF
- 8. Decode the secret message: QZZQEA QZ RQVF
Full solutions are on the downloadable answer key (PDF).