Vowel diphthongs are not that difficult to understand; all your students really need is proper guidance. When two vowel sounds come together, they form a whole new sound different from their original individual sounds. Use this vowel diphthongs worksheet to show your children some examples of vowel diphthongs. Read the words in the free printout to your kids, and make sure you enunciate the words carefully. Now, help them identify which words have diphthong sounds, and trace the lines to connect them.