First Grade English: Diphthongs & Special Vowels (oi, oy, ou, ow, oo, aw)
In the musical world of language, some vowel pairs create sounds that are so dynamic that your mouth literally moves from one shape to another while you are pronouncing a single syllable. These gliding vowel combinations are known as diphthongs. In this chapter, you will also explore special vowel partners that make unexpected sounds, including the playful pairs oi and oy, the energetic pairs ou and ow, the dual personalities of oo, and the broad sound of aw.
What Is a Diphthong?
A diphthong is a special vowel sound that begins at one mouth position and glides smoothly into a second position within the exact same syllable. When you say a diphthong slowly while looking in a mirror, you can watch your lips and jaw shift shape during the sound!
+-------------------------------------------------------------+
| THE DIPHTHONG GLIDE |
+-------------------------------------------------------------+
| |
| Position 1 Position 2 |
| (Round open lips) ===> (Narrow smiling lips) |
| /ah/ ===> /ee/ |
| |
| Result: /oy/ as in "coin" and "boy"! |
| |
+-------------------------------------------------------------+
The Word "Diphthong"
The word diphthong comes from Greek, meaning "two voices" or "two sounds." It reminds you that your voice glides between two vowel tones to create one seamless, expressive spoken sound.
The Coin and Boy Duo: OI and OY
The diphthong sound /oy/ is one of the most cheerful sounds in the English language. It is represented by two major spelling teams: oi and oy.
+-------------------------------------------------------------+
| THE /OY/ SOUND TWINS |
+-------------------------------------------------------------+
| OI -> Lives in the MIDDLE of words (coin, boil, foil) |
| OY -> Lives at the END of syllables (boy, toy, joy) |
+-------------------------------------------------------------+
The OI Team in the Center
Just like the vowel team ai, the spelling oi almost never stands at the end of an English word. Instead, it lives protected in the middle of words, surrounded by consonants: "coin," "soil," "point," "join," and "voice."
The OY Team on the Edge
When the /oy/ sound rings out at the end of a word or syllable, the letter y steps up to create oy: "toy," "boy," "joy," "enjoy," and "royal."
The Shout and Brown Duo: OU and OW
When you accidentally stub your toe, you might naturally cry out: "Ouch!" That exact sound—/ow/—is represented by two main spelling partners: ou and ow.
+-------------------------------------------------------------+
| THE /OW/ SOUND TWINS |
+-------------------------------------------------------------+
| OU -> Found in the MIDDLE of words (cloud, shout, out) |
| OW -> Found at the END or before n/l (cow, town, owl) |
+-------------------------------------------------------------+
The OU Team
The team ou appears inside words like "cloud," "sound," "mouse," "house," and "round." Notice how your mouth starts wide open and closes into a tiny round O as you glide through the sound.
The Versatile OW Team
The combination ow can say /ow/ in words like "cow," "how," "down," "clown," and "brown." However, you must be a wise reader: ow can also act as a long o team, as in "snow," "blow," and "grow." When you encounter an unfamiliar ow word, try the /ow/ sound first; if that does not make sense in the sentence, try the long o sound!
The Two Faces of OO: Moon vs. Book
The double o combination (oo) is famous for having two distinct, special vowel sounds: the long /oo/ sound and the short /oo/ sound.
+-------------------------------------------------------------+
| THE TWO SOUNDS OF OO |
+-------------------------------------------------------------+
| Sound Type | Mouth Shape | Key Examples |
| ------------+--------------------+-------------------------|
| Long /oo/ | Lips puckered out | moon, zoo, spoon, pool |
| Short /oo/ | Lips slightly open | book, look, foot, wood |
+-------------------------------------------------------------+
Long /oo/ (The Ghost or Monkey Sound)
In words like "moon," "spoon," "too," and "cool," your lips pucker forward tightly to create a smooth, ringing /oo/ sound.
Short /oo/ (The Gentle Foot Sound)
In words like "book," "cook," "look," "foot," and "wood," the sound is shorter, softer, and more relaxed. Your lips do not pucker nearly as far forward.
The AW Sound: Saw and Paw
The vowel pair aw (along with au) creates the broad /aw/ sound heard in "saw," "paw," "straw," "crawl," and "lawn." When you make this sound, your jaw drops comfortably downward, as if you were admiring an adorable puppy: "Awww!"
Practice Exercises
Exercise 1: Read the following words aloud and match each word with its special vowel sound category (/oy/, /ow/, long /oo/, short /oo/, or /aw/): cloud, coin, book, spoon, hawk, toy, clown.
Exercise 2: Fill in the blank with either "oi" or "oy" to complete each word: c-_-n (a shiny metal piece of money), and t-_ (a fun object used for playing a game).
Exercise Solutions
Solution to Exercise 1: In "cloud", the sound is /ow/. In "coin", the sound is /oy/. In "book", the sound is short /oo/. In "spoon", the sound is long /oo/. In "hawk", the sound is /aw/. In "toy", the sound is /oy/. In "clown", the sound is /ow/.
Solution to Exercise 2: For the shiny money piece, use oi to make "coin". For the play object, use oy to make "toy".