TL;DR: Spaces separate word number groups; punctuation is usually dropped or preserved depending on tool settings. Specify rules on assignments and match them when auto-grading.
Word boundaries via spaces
HELLO WORLD encodes as two groups without encoding the space itself. Missing space merges groups—primary formatting failure mode.
Punctuation stripping default
Periods, commas, exclamation marks often removed before map. “HELLO!” → HELLO numbers only. Ask if punctuation should encode separately in advanced puzzles—it rarely should.
Apostrophes in contractions
Don’t → DONT or DON T depending on tool. Standardize can’t as CANT for classroom keys to match converter output.
Hyphenated words
Twenty-one: encode with or without hyphen as TWENTYONE vs TWENTY ONE—two number groups. Pick one style in answer key.
Line breaks vs spaces
Paste from PDF may insert newline mid-word. Normalize whitespace before encode batch jobs.
Multiple internal spaces
Double space between words may produce empty token or merge—trim input in preprocessing step.
Tool consistency check
Encode “Hello, world!” on letterstonumbers.com yearly; syllabus example updates if behavior changes.
Teaching punctuation awareness
Side lesson: ciphers carry letters only; punctuation restored by human reader after decode for readability.
JSON and code snippets
CS students pasting strings with quotes—strip delimiters before cipher lab or quotes become garbage “letters” if not filtered.
Readable presentation
Encourage comma-separated output for long messages to graders when permitted—easier than 80-digit run-on line.
Apostrophe in contractions policy
Don’t → DONT encoding standardize as CANT-style for can’t—publish one convention on worksheet header.
Hyphenated word decisions
Twenty-one as TWENTYONE one group vs TWENTY ONE two groups—pick one style in answer key.
JSON snippet warning for CS crossover
Quotes in code strings pasted into cipher input become garbage letters if not filtered.
Readable comma presentation
Long messages easier to grade with comma separators when teacher permits—student choice within rubric.
Side lesson on punctuation role
Ciphers carry letters; humans restore punctuation after decode for readability.
Hyphen decision inside WELL-KNOWN
WELL-KNOWN can be encoded three ways, and only one of them should be on the key. If the hyphen is dropped and the parts stay separate, you get WELL and KNOWN: 23 5 12 12 and 11 14 15 23 14. If the hyphen is dropped and the parts join, you get WELLKNOWN as one group. If the hyphen is kept as a printed symbol, the tool may skip it or throw it away. Pick the first policy for this worksheet: two groups, hyphen not encoded. Write that policy above the item, not in a footer the student never reads.
Decode both groups before you accept a paper. A student who joins the word will have one group whose length is the sum of the parts. That paper followed a different policy, not necessarily a different alphabet. You can still mark the letters right and the grouping wrong, but only if the policy was visible. A hidden policy turns a formatting choice into an alleged math error.
Apostrophe drop in the contraction IT’S
IT’S drops the apostrophe under the usual school rule and becomes ITS, which is 9 20 19. The word ITS without an apostrophe encodes the same way. That collision is the lesson. The cipher cannot see the difference between the contraction and the possessive once the mark is gone. If the assignment needs that difference, the cipher is the wrong tool and the sentence should stay in plain text.
Do not encode IT’S as I T S with a leftover 27 or some invented code for the apostrophe unless the worksheet says so in the same line as the item. Invented punctuation codes are a new cipher. They should be taught as a new cipher, with one punctuation mark and one number, on a day when the alphabet map is already fluent. Mixing them into an ITS item makes every answer look arbitrary.
Three spaces between BLUE and WHALE
BLUE WHALE with three spaces is still two words. BLUE is 2 12 21 5. WHALE is 23 8 1 12 5. A tool that collapses whitespace will return two groups. A tool that emits an empty group for each extra space will return empty slots between them. Paste a deliberate triple space and look at the output before students do. If you see an empty slot, tell the class to use single spaces. If you see two clean groups, tell them extra spaces are harmless in this tool, this term.
Retest when you change browsers. A school image that updates over the summer can change how a textarea treats whitespace. Last year’s note about harmless extra spaces should not be copied into this year’s sheet until you have pasted BLUE, three spaces, WHALE again. The test takes one minute. The wrong note wastes a period.
Retest note for BLUE WHALE after a browser update
Write the retest result on the worksheet master, not in a chat thread. “March image, BLUE plus three spaces plus WHALE, two groups, no empty slot.” Include the numbers you expect: 2 12 21 5 and 23 8 1 12 5. A future editor can compare in one paste. A chat message from last spring will not be open when the image updates, and the editor will guess.
If the new image emits an empty group, change the student instruction to “type one space yourself, do not copy spacing from the PDF.” Do not change the cipher key. The letters of BLUE and WHALE did not change. Only the instruction about how spaces are produced changed. Keep those edits in different sentences so a hurried revision does not “fix” the numbers while fixing the spacing note.
