Read the section on the Great Vowel Shift in your textbook. When you've finished, practice the four stages in the video exercises below.
Click the Play button to start the clip for each stage. You can start it over at any time by clicking the Rewind button. At any point, you can click on a phoneme to hear it pronounced. When you've learned a stage, click the button at the bottom of the player to move to the next one.