Watch this video if you need to remember how to pronounce -ed at the end of past simple verbs.
Would you like to try this exercise? Apart from deciding on the right pronunciation, you can also listen to a native speaker reading the text.
You can also play these games.
If you want to try the same phonemic chart I used in class, and be able to listen to the sounds, you may visit this website (scroll down the page to see the chart)
If you want to download the app for your mobile device for free (iOs only), click here.