Lesson 42: The FLSZ RuleNew Concept: The FLSZ Spelling Rule: Double F, L, S, and Z After a Short Vowel

Keyword: 
FF — cliff; 
LL — bell; 
SS — mess; 
ZZ — buzz

Where it appears: At the end of a one-syllable word, after a single short vowel.

Instructional Note: This rule is sometimes called the "floss rule" because the word floss itself follows the pattern (FL + OSS). Students have likely seen these spellings already, this lesson gives the rule a name and makes the pattern explicit.

Quick Tip: The FLSZ rule applies only when one short vowel comes right before the final F, L, S, or Z. If there is a consonant before those letters, or if the vowel is long, you do not double.

Extra worksheets 

DAY 1 — Steps 1 through 6 
Step 1: Phonemic Awareness  

Part A — Blending
Say: “I am going to say some sounds one at a time. Squish them together into one word. Ready?”
/o/ /ff/ → off
/h/ /ĭ/ /ll/ → hill
/p/ /æ/ /ss/ → pass
/s/ /t/ /ĭ/ /ll/ → still

Part B — Segmenting
Say: “Now I will say a word. Break it into its sounds and count them on your fingers.”
well → /w/ /ĕ/ /ll/
buzz → /b/ /ŭ/ /zz/
fill → /f/ /ĭ/ /ll/
toss → /t/ /ɔ/ /ss/

Step 3: Auditory Drill  (Hear the Sound, Write the Grapheme)

a
i
u

Step 5: Word Building

• clap
• trip
• frog
• bend

Step 6: New Concept

Introduction
You have already seen words like hill, mess, and staff in your reading. Today you are going to learn the rule that explains why those words are spelled the way they are.

Here is the rule: when a one-syllable word ends in the sounds /f/, /l/, /s/, or /z/, and there is just one short vowel right before that sound, we double the final letter.

F doubles to FF: cliff, staff, sniff, huff.
L doubles to LL: hill, bell, ball, doll, full, spell.
S doubles to SS: miss, boss, dress, glass, floss.
Z doubles to ZZ: jazz, fizz, buzz, fuzz.

Say cliff. Hear the short I? One short vowel, then /f/ at the end — so we double: FF.

Say hill. One short vowel I, then /l/ at the end — double the L: LL.
Say miss. One short vowel I, then /s/ at the end — double the S: SS.
Say buzz. One short vowel U, then /z/ — double the Z: ZZ.

The word floss is a great way to remember all four: FL-OSS — it uses the rule itself.

Read and Spell Together
READ                          SPELL
I do: cliff, bell                           I do: staff, mess

We do: stiff, huff, puff, hill, sell, well, miss, boss, dress, buzz, fizz

We do (spell): sniff, fill, gross, fuzz

Step 10: Dictation
Say: “I am going to read a sentence aloud. Listen carefully, then write it. When you are done, we will check it together using CAPS.”

"Do not spill the fizz!"
​
CAPS Check: 
C = Capital letter at the start ​
A = Appearance of letters ​
P = Punctuation at the end ​
S = Spelling