Secret code maker
Type a message and get a printable code-breaker sheet: the message in symbols, numbers or shifted letters, a line under each to write on, the key printed on the sheet and an answer key. Free, no sign-in.
To save a PDF, choose Print, then “Save as PDF” as the printer. Only the sheets print.
46 coded letters. The answer key page has the message decoded.
How to use it
- Type your message, or press a sample. Letters are coded; spaces and . , ! ? ' - : ; stay as they are. Up to 200 characters.
- Choose the kind of code. Symbols and mixed-up numbers use a fresh random key for every sheet. Plain numbers is A = 1, B = 2. A shift cipher moves every letter the same number of places along the alphabet.
- Keep “Print the key on the sheet” ticked for students who decode with the key. Untick it for a challenge where they have to crack it.
- Press Print. The answer key page has the message decoded. Add a “Write your own” page if students will code their own messages.
Ideas for class
- A treasure hunt: put each next clue in code, so students decode it to find the next hiding place.
- A warm-up or exit ticket: a coded sentence about the day’s lesson that students decode before they leave.
- Learn about history: a shift cipher is the kind of code Julius Caesar is said to have used, and it works well after reading about codes and spies.
- Pattern spotting: untick the key and ask which letters or short words repeat in the coded message.
- Student-to-student messages: students write their own message, code it with the key on the “Write your own” page and trade.
- Different codes for different groups: plain numbers for younger students, a shift cipher for older ones.
Related
Questions
What kinds of code can I make?
Four: a symbol for each letter, a number for each letter (in a mixed-up order), plain numbers (A is 1, B is 2, up to Z is 26), and a shift cipher where each letter moves along the alphabet by a number you choose from 1 to 25.
Is the key printed on the sheet?
Yes by default, in a box at the bottom of the page. Untick “Print the key on the sheet” to leave it off. The answer key page has the message decoded.
Why do the symbols look the same on any printer?
The symbols are shapes that are solid or hollow, drawn in black, so no two look alike on a black-and-white printer.
Can I get the same code again?
Yes. Symbols and mixed-up numbers come from a number saved in the sheet’s address, so Share gives the same key and the same sheet. Plain numbers and shift ciphers need no random key.
What happens to numbers in my message?
In a symbol or shift code, digits are left as they are. In a number code they would be confused with coded letters, so digits are left out and the page tells you.
Is my message private?
Yes. It is coded in your browser and is never sent to us. Share puts it after the # sign in the link, which our server never receives.
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