When adding a suffix that begins with a consonant, the general rule is to

The “doubling up” rule (or the “1:1:1 rule”) is one of the few rules in English spelling that is correct most of the time. Given how confusing English can be, we find this reliability oddly comforting. Let’s look at how it works.

What Is the Doubling Up Rule?

The doubling up rule states that, when adding a vowel suffix (e.g., “-ing” or “-ed”) to a single-syllable word that ends with one vowel followed by one consonant, we should double the final consonant. For instance, “dig” gains an extra “g” when changed to “digging.” Additional examples include:

As you can see with “starry” (i.e., lit by stars), “y” is sometimes treated as a vowel for this rule. Other words like this include “sunny,” “blurry,” and “furry.”

The Exceptions

The only universal spelling rule in English is that there’s actually no universal spelling rule in English. As such, we need to mention a few exceptions: words that end in “w,” “x” or “y.” These letters aren’t usually doubled in English, so single-syllable words that end in a vowel plus “w,” “x” or “y” don’t require doubling the final letter when adding a vowel suffix:

Multi-Syllable Words

Things get trickier with words more than one syllable long. Some still require doubling the final consonant when adding a vowel suffix, such as:

These are generally words where the final syllable is stressed.

When the final syllable of a multi-syllable word is not stressed, however, the final consonant is not usually doubled. Examples include:

In some cases, whether to double the final consonant depends on the suffix added. “Prefer,” for example, gains an extra “r” in “preferred” or “preferring.” This is because, in both, the final syllable is stressed. However, no doubling is required in “preference,” since the final syllable here is unstressed.

Multi-Syllable Exceptions

There are some words that don’t follow the pattern above, but with which we still double the final letter when adding a vowel suffix to clarify the pronunciation.

With “format,” for example, we typically place the stress on the first syllable. But we still double the “t” when adding a suffix to show that it is pronounced with a short vowel sound. Thus, we pronounce “formatted” as “for-mat-ed,” not “for-mate-ed,” and the double “t” before the suffix helps to clarify this.

There are also some words that end in an “-l” that are conventionally spelled with a single consonant in American English, but that take a double consonant in British or Canadian English. For example:

In other words, multi-syllable words can be tricky! Using the pronunciation to guide your spelling will usually help, but don’t forget to check specific words in a dictionary if you’re unsure whether to double the final consonant when adding a vowel suffix. Likewise, it’s important to proofread your work carefully and double check any words that you’re not 100% sure are spelled correctly.

Are you ready to learn everything you need to know about teaching the Rules for Adding Suffixes to Words? Hang on, because that’s what this video series is all about!

With videos and free printables each week, it will be similar to our popular video series on Teaching Syllable Types.

Before we dive in too far, I wanted to spend some time today defining some terms and explaining why all of this is important to our readers and spellers.

First, let’s quickly define a three terms just to be sure we’re all on the same page.

1. Suffixes –  Suffixes are parts of a word that are adding to the end of a base or root word. Suffixes add or change the meaning of the base word. For example, in the word jumped, jump is the base word while ed is the suffix. In this example, the suffix tells you that the action {jump} was done in the past.

The most common suffixes are the inflected endings: -s, -ed, -ing, and -es.

2. Vowel Suffixes – Vowel suffixes start with a vowel. These can be the trickiest to add onto words because they have more rules associated with them. {We’ll explore this in more detail later in this series.} Some examples of vowel suffixes include, but are not limited to, -ing, -ed, -ish, -er, and -able.

3. Consonant Suffixes – Consonant suffixes starts with a consonant. These include suffixes like -less, -ful, -ness, and -ly.

Watch the YouTube Video:

Why do Kids Need to Learn these Rules Anyway?

Believe me when I say that teaching these rules is not a waste of your time. As a matter of fact, you’ll find it’s quite the opposite. Breaking down the steps of spelling and decoding words with suffixes is important for ALL our learners, especially our struggling learners.

Let’s three important reasons kids need to learn these rules: 

The first reason kids need to learn these rules is that they are consistent rules. Although nearly every rule has exceptions, rules for adding suffixes to words is pretty reliable. That’s good news!

The second reason these rules are important is that they help learners break apart longer words into chunks to decode them easier and faster. For example, if a learner comes across the word smiled, they can be taught to look for the -ed chunk as they decode it. They can also be aware of the e-drop rule, which means that the vowel is a long i, not a short i.

The third reason learning these rules is important is that they help learners spell words. For example, if you’re trying to add -ing to shop, knowing the y to i rule helps learners spell shopping, not shoping. {This is known as the 1-1-1 doubling rule, which we’ll get to!}

Rules for Adding Suffixes Links:

Click on the images OR the links below to find the posts, videos, and free printables from this six-part series.

Enjoy teaching!
~Becky

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