What is the Floss Rule?
The Floss Rule is one of those simple phonics tricks that can make a big difference in your child’s spelling. You can find our floss rule cards in our letter sounds flashcards deck which includes ff, ll, ss, zz. I included them so that you could use them when practicing floss words.
The Floss Rule is included at the back of those cards for your easy reference.
A helpful way to explain it to your child is:
“Double f, l, s and z at the end of a short word (1 syllable word) after a short vowel.”
Keeping it this simple makes it much easier for young learners to remember. I usually teach floss rule when kids are 5-6 years old or whenever you find your child is ready to grasp this concept.
Easy Ways Parents Can Teach the Floss Rule
1. Start with a few clear examples
Show pairs like hill vs. hip or miss vs. mist. This helps your child see and hear the difference. Focus on just a few words at a time so it doesn’t feel overwhelming.
2. Use flashcards for quick practice
Phonics flashcards are perfect for this rule. Use the cards to form words and have them fill in the end by asking your child to decide whether to “double” and “not to double” based on the spelling rule. This turns learning into a simple game and builds confidence.
Because o here makes the short vowel sound like in octopus, we double it!
Let's try another one!
Because oa makes 1 sound and it is a long vowel sound like in boat, we do NOT double it!
3. Say the sounds out loud
Encourage your child to sound out words slowly: /b/ /e/ /l/. Then ask, “Does it end in l after a short vowel?” If yes—double it. Hearing the sounds helps the rule stick.
4. Make it interactive
Let your child build words using letter tiles or write them with markers. When they double the last letter, they can even say “double!” out loud—it makes the learning more memorable.
5. Practice in real reading and writing
Point out words like glass or full when you see them in books. When your child is writing, gently remind them of the rule and let them try it themselves.
6. Keep it low-pressure
There are a few exceptions (like gas), so don’t worry about perfection. The goal is to help your child recognise the pattern over time.
With regular, playful practice, the Floss Rule becomes second nature—and tools like phonics flashcards can make that practice quick, engaging, and effective at home!