1. Overview of the FLoSS(Z) Spelling Rule

Once students know their short vowel sounds and understand closed syllables, they are ready to learn the FLoSS(Z) spelling rule, which is used in words like puff, fill, mess, and buzz.  

The FLoSS(Z) rule, also known as the double-consonant spelling pattern, explains when to double the ‘f’, ‘l’, ‘s’, or ‘z’ at the end of a word. It says:

(Print a copy (opens in new window) of this rule for your students or to display in your classroom.)

The FLoSS(Z) rule is one of four short vowel spelling rules. The other three short vowel rules — '-ck', '-tch', and '-dge' — have their own skill explainers. We typically introduce '-ck' first followed by FLoSS(Z) because they both follow a straightforward pattern, making them easier for students to understand. We introduce '-tch' and '-dge' later because they have more exceptions and require more decision making during spelling. 

Watch first-grade teacher Jenifer Rogers introduce the FLoSS(Z) rule to her students at Burgess-Peterson Academy in Atlanta.

The structured literacy approach is systematic and cumulative. That means each time you teach a new phonics skill, you need to consider how it interacts with other skills. 

Here are some other phonics skills that connect to the FLoSS(Z) spelling rule. You'll want to talk about these interactions explicitly when you come across them. 

Glued Sound -all

The glued sound '-all' follows the FLoSS(Z) rule, but the 'a' doesn’t make its usual short sound. You can learn more about '-all' and other glued sounds in our Glued Sounds Skill Explainer.

Ending Blends

When teaching the FLoSS(Z) rule, remind students that short vowel words ending in a consonant blend — like mask and shelf — do not double the final consonant. The final consonant is only doubled when there’s just one sound after the short vowel.

We do NOT need students to memorize high-frequency words that have FLoSS(Z) and follow a regular spelling pattern. Now that you have explicitly taught FLoSS(Z), they can sound out the words for reading and spelling. Below are some high-frequency words containing FLoSS(Z) that you can easily incorporate into your phonics lessons.

See the full list of Dolch words separated by phonics patterns.