The Floss Rule: What is it? Free Activities for Teaching

December 8, 2022

The FLOSS rule is a spelling rule that is known by other names in K-2 classrooms. Some call it Sammy Loves Friendly Zebras others call it the FLSZ rule, and others call it the Bonus Letter Rule. No matter what you call this rule, it means the same thing.

The FLOSS rule is when you double the last letter of a word that has the following: 1 syllable, 1 short vowel, and ends in 1 of the following sounds /f/ /l/ /s/ /z/. When teaching students about this rule, I explain that it is a 1-1-1 rule and we need to check for these before we decide if the last letter is doubled when we write it.

Before I continue, I wanted to let you know that this information is available in video format. Just click below watch or listen to this information:

To read this information, just keep scrolling!

Description of the floss rule as a 1-1-1 rule.

Tips when teaching the FLOSS rule:

When teaching students about the FLOSS rule and what it is, there are a couple things to keep in mind. First, this is a spelling rule or spelling generalization, so this doesn’t affect the way we read words, but instead, it will affect the way we spell our words. Also with any spelling “rule”, there will likely be some exceptions to the rule and that is the case here!

Second, some teachers and curriculums choose not to teach the doubling of the z with this rule and that is for two reasons. First, there aren’t that many words in the English language that end in the double z, and second, some of the exceptions to this rule are tricky when thinking about the /z/ sound. For example, is, his, and was seem to follow the 1-1-1 rule because they have 1 syllable, they have 1 short vowel sound, and they end in the /z/ sound.

I should make it clear that I still choose to teach the z in this rule because the words I mentioned above (is, his, was, etc.) are all heart words I teach my students about so I expect them to know how they are spelled. Also, I explain to students that in order for this rule to apply, the words need to end in a /z/ sound and also be spelled with the letter z. Taking those two things into account, my students have had success with this rule!


Activity 1: Does the FLOSS rule apply?

Step 1 in teaching this rule is to explain to students what the rule is (as mentioned above) and to give them some examples of these words.


After students understand what the rule is, there are some activities I like to use with my students to help them practice applying this rule. The first thing I like to do is show my students word cards with a single letter at the end and we need to look through our 1-1-1 rule to see if we should apply the floss rule and double the last letter.

Here is what this looks like:


I like to put the 1-1-1 rule on the board with blank boxes to check off. Then I get a bunch of index cards and write words on them with a single letter at the end (some will apply to the floss rule and others won’t). Examples include: cuf, spil, mes, tap, hat, box, wheel, chief, buz.

I tell my students that some of these words are correct as is, and others will need to add the double letter at the end. I flip each card and as a class, we walk through the 1-1-1 rule and apply double letters as needed! This is a great way for students to see words that apply and words that don’t.


Activity 2: Encode words and sentences:

The next activities I like to use with my students give them opportunities to encode or spell, these different words. To begin, I made these free cards with images of words with the FLOSS rule. To use these, I simply flip a card, we all say the word aloud, and then students will write the word on their whiteboards or build the word with letter magnets.

Don’t forget when having students practice dictation, to have them practice words in isolation as well as words in a sentence. Some examples sentences for the FLOSS rule include:

Will Bill get the shell?

There was fuzz on the pill.

Jill is on the hill with a bell.

When doing sentence dictation, we always make sure to count the words in a sentence aloud before writing. Then I slowly repeat the sentence numerous times as students write it down on their boards. In the end, we check for punctuation, capitalization, and spelling.



Activity 3: Phoneme Manipulation:

Another way I like to practice encoding with the FLOSS rule is to have students practice phoneme manipulation. Here students will write a word, then change the last phoneme to show the double letter. This can be done with letter magnets or by writing on their whiteboards. It would sound like this: “spell pick. Change /k/ to /l/.” “Spell bet. Change /t/ to /l/.” Here are some more examples for your students:



Activity 4: Partner Games (Spin, Say, Spell):

Lastly, I made some fun games to help students practice this rule on their own or with a partner! These games are called Spin, Say, Spell and I have 3 free game boards for you to use!

These free game boards have students spinning the spinner, saying the words aloud, and spelling them! Four of the six words have the FLOSS rule applied to them and the others don’t. This way students will need to look closely at the words to determine which words have the double letter at the end and which do not.

To grab all the free word cards and game boards, just click below:


I hope you enjoy these activities for teaching the FLOSS rule. Do you teach this with your students?! If so, what do you call this rule? Let me know in the comments!

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  • Susan, I am so thankful I have found your site, and I love your teaching knowledge, wisdom and techniques. I had reached a point, in homeschooling my 5.10 year old granddaughter, for over 4 years now, that I was ready to teach her digraphs and blending. She will be going to public 1st grade this year. She already knows how to read, write beautifully (proficient in sizing and spacing of letters),