The Change Y to I Rule: What It Is and How to Teach It

By Lauren Kline, M.S., CCC-SLP, A/OGA, C-SLDI

If your students stumble when adding endings to words like "happy," "carry," or "try," they're not alone. The change y to i rule is one of those spelling patterns that trips kids up -- until they learn the logic behind it. And there absolutely is logic.

The Rule

When you add a suffix to a word that ends in the letter y, change the y to an i -- unless the suffix starts with the letter i.

That's it. One rule, one exception.

How It Works

Take the word carry. If we want to add -ed, we change the y to i first:

• carry → carri + ed → carried

Same thing with other suffixes that don't start with i:

• happy + ness → happiness

• easy + er → easier

• plenty + ful → plentiful

• try + es → tries

• fry + ed → fried

The y drops, the i takes its place, and the suffix attaches.

The Exception

If the suffix starts with the letter i (like -ing or -ish), keep the y. Why? Because English avoids doubling up on the letter i.

• carry + ing → carrying (not "carriing")

• try + ing → trying (not "triing")

• baby + ish → babyish (not "babiiish")

Once students understand the reason for the exception -- avoiding that awkward double i -- it sticks.

Why SLPs Should Care About This

If you're working with students on morphology, multisyllabic words, or written language goals, this rule comes up constantly. Think about how often your therapy targets involve adding -ed, -ing, -es, or -er to base words. If a student is working on past tense in speech, they're going to encounter this pattern in writing too.

Teaching the rule explicitly -- rather than hoping they absorb it -- gives them a tool they can apply independently. That's the difference between memorizing individual words and understanding a system.

How to Teach It

1. Start with the pattern. Show 4-5 words that end in y. Add the same suffix to each. Let the student notice what changes.

2. Name the rule. State it clearly: "When we add a suffix to a word ending in y, we change the y to i -- unless the suffix starts with i."

3. Practice the exception. Show the same base words with -ing. Ask why the y stays. Let them figure out the double-i problem.

4. Word building. Give students base word cards and suffix cards. Have them build words, applying the rule each time.

5. Sort it. Create a two-column sort: "change y to i" vs. "keep the y." Students sort words and explain their reasoning.

The Bigger Picture

This is one of three major suffixing rules in English (along with the doubling rule and the drop-e rule). When students learn all three, they have a framework for spelling the majority of suffixed words they'll encounter. That's powerful -- especially for kids who've been relying on memorization and guessing.

Spelling patterns aren't random. When we teach the rules explicitly, students stop seeing spelling as something they're bad at and start seeing it as something that actually makes sense.

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Lauren Kline is a speech-language pathologist and structured literacy specialist. She writes about the intersection of speech, language, and literacy at [lkslo.com](https://www.lkslo.com).