Ok, so teaching time isn't the hardest of tasks, but neither is it the easiest. Most of your students will probably be perfectly fine with telling the time in their own language (L1) but when it comes to all the slightly confusing terminology in English, they will probably struggle.
I found this out the hard way the other week when, having planned on a quick review of telling the time, before introducing quarter past, quarter to and half past, I discovered that my class were having difficulties with simple past and to times. So, must of the lesson was spent reviewing what i thought they knew. With me stood there wishing I had some fun, interactive way of doing it, in stages to help them understand.
Hence Tell Time with Tim (which i used the following week with great results).
It starts off helping your students with the simple o'clock's, then moves onto splitting the hour into five minute chunks, before looking at the split between past and to and details of 5, 10, 15, 20 and 25 past and to.
Then there is the chance for you students to produce the time that you tell them, first with a guide to the above and then with no help. Simply press the minute and hour buttons to advance each hand of the clock to the desired time.
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Have a look at Matt-Erials Time Dice for more practice telling the time.