A dipthong is the term for a vowel sound that is created by two vowels working together. There is only one sound, but two vowels are used to make the sound. Some describe the sound as a "gliding" from one of the vowels to the other without separating the sound.
The "oy" sound can be made with the following vowel pairs: oy, oi.
The "ow" sound can be made with the following vowel pairs: ow, ou
The "a" sound made with ai:
Diphthong Words: OU OW Sounds Game
Pronouncing Vowel Sounds in Spanish
Oi Oy Sounds Game
Ch Sh Wh Sh Sounds Game
oi oy sounds worksheets- Diphthongs