How Do You Make a Thanksgiving Cryptogram?

Make a Thanksgiving cryptogram by writing a short original message, replacing each letter with another letter according to one consistent key, and giving players space to work out the message. For a first puzzle, keep the spaces and punctuation visible and offer a few clues.

This guide uses a beginner-friendly Caesar shift, one kind of substitution cipher. It is a holiday word puzzle, not a way to protect private information. Harvard’s CS50 explanation describes the shifting method and its weakness as modern security.

Start with a message you wrote yourself

Choose a brief sentence that makes sense without knowing your family’s private jokes. A message about passing a dish, telling a story, or welcoming a guest can provide the Thanksgiving connection.

For the worked example, use this original line:

PASS THE PIE AND SHARE A STORY.

Write the answer first and check its spelling. Avoid unfamiliar names, abbreviations, and several long words in your first puzzle. The purpose is to give someone a satisfying message to uncover, not to make the answer impossible to recognize.

Build one clear substitution key

In a shift of three, A becomes D, B becomes E, and so on. At the end of the alphabet, X becomes A, Y becomes B, and Z becomes C. The University of Waterloo’s cryptography lesson illustrates this three-place substitution.

Here is the full key, split into two parts so it is easy to copy. Read from the Plain row to the Code row when making the puzzle.

Plain: A B C D E F G H I J K L M
Code:  D E F G H I J K L M N O P

Plain: N O P Q R S T U V W X Y Z
Code:  Q R S T U V W X Y Z A B C

Use this same key for every letter. The two S letters in PASS must both become V. A repeated letter does not get a new replacement just because it appears later in the sentence.

Keep the completed key with your answer sheet. The International Spy Museum’s cipher activities similarly emphasize retaining the key for decoding; its optional wheel activity offers another way to explore letter substitutions.

Turn the sentence into a puzzle

Work one word at a time. PASS becomes SDVV because P becomes S, A becomes D, and each S becomes V. Continuing through the original sentence gives:

SDVV WKH SLH DQG VKDUH D VWRUB.

Copy that coded line onto a clean sheet. Leave a blank line underneath for the answer, or draw one small answer box below each coded letter. Keep the word spaces in the same positions. There are seven words and twenty-four letters in this example; the full stop stays a full stop.

Do not give players the complete key unless you want a straightforward decoding exercise. Both versions are valid: using a supplied key and discovering a hidden key are simply different challenges.

Offer clues in useful stages

Tell players that this puzzle shifts every letter by the same amount. For another hint, say that the coded letter S stands for the original letter P. Someone who wants a smaller first step can begin with just SDVV and the clue that the word means handing something to another person.

To decode, reverse the direction: find a coded letter in the Code row and read the Plain letter above it. In this example that is the same as moving three letters backward, wrapping around when necessary. Harvard’s explanation of reversing the shift describes this relationship.

Let people work together, use pencil, or ask for the full key. A clue is part of the activity rather than a penalty.

Test the finished sheet before sharing it

Decode your clean copy rather than checking only the original notes. One mistyped letter can create a word that no amount of guessing will fix. Check that repeated letters match, spaces remain in place, and the answer uses the same spelling throughout.

The example should decode to PASS THE PIE AND SHARE A STORY. If it does not, compare each pair against the key before handing it to anyone else.

Keep the answer on a separate page or fold it out of sight. You can set the puzzle beside spare pencils after the table has been cleared, with no timer required. Once someone finishes, invite them to write a new Thanksgiving message and swap roles: the next puzzle can be theirs.