The Floss Rule

Introducing the Floss Rule

There are four letters that the Floss Rule applies to: f, l s, and z.

It is called the floss rule because three of these letters are in the word floss. If you take on a French accent and call it Ze Floss Rule, all four letters will be prepresented.

The Rule:

If the word ends in f, l, s, z and there is a short vowel before it, then you double the f, l, s, or z.

Three things to keep in mind:

  • You only pronounce  one consonant even thought there are two
  • If you are reading and see a double f, l, s or z then you must pronounce the vowel as a short vowel
  • If the “s” says /z/ you do not double (i.e. has, is)

Part of the closed syllable family

Exceptions to the rule:

There are exceptions to this rule.  Some of the excepts have to do with the etymology (source) of the word.  For example, you do not double the s in bus because it comes from the word autobus and you do not double the s in gas because it comes from the word gasoline. This is information that your students will find interesting so be sure to share it with them as it helps to dispel the myth that English does not follow pattern and is unpredictable.

Common exceptions: pal, us, if, yes, this

Prerequisite skills

Student understands long and short vowels.

Students know what a suffix is.

Student know what open and closed syllables are


Letter tiles

Word lists

Words ending in ff:

off, stiff, staff, cliff, whiff, puff, sniff, stuff, scoff, cuff, scuff,
bluff, gruff, jiff, huff, buff, fluff

Words Ending in ll:
hill, spill, spell, will, well, fell, tell, yell, sell, sill, fill, bill, mill, bell,
still, swell, drill, ill, call, Jill, bull, cell, chill, dill, doll, grill, pill,
shell, skull, skill, smell, thrill

Words Ending in ss:
miss, kiss, class, grass, gross, boss, floss, mess, dress, toss,
boss, miss, pass, fuss, chess, mass, less, moss, fuss, hiss,
press, cross, stress, guess

Words Ending in zz:
buzz, fizz, jazz, frizz, fuzz

Phonological Activity

Guided Practice

Independent Practice

Florida Center for Reading Research

Caterpillar Roll and Read



Using phoneme-grapheme spelling, say words and have students write them out:

Floss rule words: Grass, fizz, shell, drill, buzz, sniff, cuff, dress

Mixing floss and non floss words: elf, feel, staff, boss, bus, peel , chess, gas, fell