Learning to tell time equals earning a watch in our home.
Each of my kids at some point in toddler-hood decide that they want a watch (usually before Kindergarten). Since so much in our world is digital, kids don't have to learn how to tell time to know what time it is. Once they can read numbers, they can read time.
Back in the day with Tater, I decided to reward her with a watch only after she learned how to tell time. Once she did, I ordered her a princess watch from Disney that had her name on it. She loved it! (and miraculously she still has it all these years later)
E-Dog did the same...wanted a watch, so then was more motivated to learn. He currently has two watches which he occasionally wears at the same time.(Not to be fashionable, mostly because he hoards things. Look for him on A&E.)
Dubs is working on telling time and I think he's just about got it. We used a number chart poster (1-100) and his clock puzzle. It's so exciting and sweet to watch your kids learn anything, but especially something as complicated as telling time.
This clock puzzle was a fantastic investment for us. (I've always liked Melissa and Doug's puzzles, but this one in particular has been very beneficial.) Whether you get it for your family or as a birthday present for another child, it's really time well spent.