Diphthongs are made when two weak vowels (i, u, y) are used together or when a weak vowel is combined with a strong vowel (a, e, o).  When these two vowels come together they are pronounced as one syllable (one sound).  Play the audio and repeat the words after the speaker.  Especially focus on the targeted vowels.  In the exercise below, play the audio and repeat the words expressed by the speaker.  Focus in on how the diphthongs are pronounced.