How can the same letters make two sounds?

English reuses its letter teams. Oo picked up two pronunciations over the centuries, and both stuck. Kids handle it happily once each sound has an anchor word: moon and book.

Is there a rule for which sound a word takes?

Not a reliable one. Oo before k usually takes the book sound (look, cook), but most other words have to be heard, which makes this a listening skill. That is the point of the sort: training the ear to make the call, then trusting it.

1st grade the two sounds of oo

1st grade the two sounds of oo worksheets

Oo spells two sounds: moon's long call and book's short push. First graders say each word aloud and sort by what they hear, pure ear training on a high-frequency team.

Free printable PDF worksheet, aligned to Common Core RF.1.3.c.

Each print is a different sheet with its own answer key. You don't need to sign up.

The kind of words you'll sort

Write each word from the bank in the correct column.

tookbootscoopsmoothmoonfootwoolbook

Columns: oo as in moon and oo as in book. "scoop" belongs under oo as in moon; "book" belongs under oo as in book.

Every print pulls a new set of words at this level, so a make-up test or a second sibling gets a different mix.

What's on a 1st grade sheet

1st grade sheets draw from 31 words, 10 to a page. 1st to 3rd grade print from the same 31 words. What changes is the standard, RF.1.3.c here. 2nd grade sheets print 14 to a page.

Some of the words:

foodzoopoolschoolballoonnoodlelookgoodhoodcookie

Sorting. Write each word from the bank in the correct column. 10 words per page.

Every version prints on US Letter or A4, with its answer key on the last page.

How to teach this

Establish the anchors first: moon (long) and book (short). Every word gets tested against both anchors aloud. If your child whispers each word before placing it, the sheet is working exactly as intended.

Watch for: The spelling gives few clues (oo before k usually says the book sound: look, took), so the ear decides. This sort cannot be done silently, and that is by design. The book sound hides in some of the most common words kids write: good, look, took. Misreading them with the moon sound is the error this sheet targets.

Common questions about 1st grade the two sounds of oo

How can the same letters make two sounds?: English reuses its letter teams. Oo picked up two pronunciations over the centuries, and both stuck. Kids handle it happily once each sound has an anchor word: moon and book.
Is there a rule for which sound a word takes?: Not a reliable one. Oo before k usually takes the book sound (look, cook), but most other words have to be heard, which makes this a listening skill. That is the point of the sort: training the ear to make the call, then trusting it.

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Aligned to Common Core RF.1.3.c. Reviewed by the One more sheet team. Content version 241, updated October 2026.

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