The FLOSS rule

After a short vowel at the end of a one-syllable word, f, l, s and z are doubled. Doubling changes nothing about the sound.

Word endings

-ff -ll -ss -zz FLOSS_01

Strong rule · High reliability · Common · Beginner · Spelling

• /f/ /l/ /s/ /z/ doubled consonants: off, bell, grass, buzz

Where Wiggler teaches it: Skill 5: Glued Sounds & Spelling Basics

Child explanation

Off, bell, grass and buzz all end with two of the same letter. You only say it once.

The rule

In a one-syllable word ending with a short vowel and one of f, l, s or z, the consonant is doubled. The doubled letter makes exactly the same sound as a single one.

What is really going on

Primarily a spelling convention, and named for the word floss, which contains three of the four. Its value for reading is the inference it licenses: a doubled final consonant signals a short vowel, the same information the ck rule carries. The common exceptions are if, of, us, bus, yes, this, gas, plus and pal.

Position in the word

• End of a word — A one-syllable word after a short vowel. For example: off, bell, grass, buzz.

When this rule works

• One syllable, one short vowel, ending in f, l, s or z.

When this rule does not work

• The vowel is long or a team: leaf, feel, goose — though feel and goose double anyway for other reasons.
• A consonant comes before: self, milk, help.
• The word is one of the common exceptions below.

Examples

Easy examples

off, bell, grass, buzz, will

More examples

cliff, stuff, sniff, tell, fell, small, spell, miss, kiss, class, dress, cross, fizz, jazz

Pseudo-words

Made-up words that follow the rule. A child who reads these has the pattern rather than the vocabulary.

blaff, shell, priss

Exceptions

• Common words with a single final consonant: if, of, us, bus, yes, this, gas, plus, pal, his, has, was. Mostly high-frequency function words that escaped the convention.

Contrast pairs

• bell versus pal — The rule and one of its common exceptions.
• miss versus this

Teacher note

Teach with the ck rule as one idea: after a short vowel at the end of a short word, English doubles up. Both carry the same information for a reader, and learning them together makes each more memorable. Flag it explicitly as a spelling rule — its reading value is only the short-vowel inference.

Learn these first

• The five short vowels — a e i o u in a closed syllable — A single vowel with a consonant after it and nothing else is usually short. This is the rule that makes CVC words decodable.

Related rules

• CK after a short vowel — ck — One sound, /k/, and a strict position rule: ck only ever follows a short vowel at the end of a syllable. Never at the start of a word.
• TCH after a short vowel — tch — Three letters, one sound, and the same position rule as ck: tch follows a short vowel, ch follows everything else.
• DGE after a short vowel — dge — The /dʒ/ sound spelled for a short vowel. Bridge, badge and judge take dge; large, huge and change take ge.
• The five short vowels — a e i o u in a closed syllable — A single vowel with a consonant after it and nothing else is usually short. This is the rule that makes CVC words decodable.

• Previous in Word endings: Y becomes I before a suffix — y + suffix → i — Happy becomes happier, cry becomes cried, baby becomes babies. A reliable change, and one that explains a lot of otherwise odd-looking words.
• All reading rules

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