LoLo (age 5) is just starting to tell time, and I am really working hard on reinforcing this skill at home. The hardest part was finding a product that allowed you to manipulate the hands and give a numerical readout too, but without letting the kids check the answer. I found the perfect thing: Learning Resources The Primary Time Teacher Junior 12-Hour Learning Clock.
This clock is just the right size for little hands, is very durable and strong (holds up to beatings by a toddler...or 3), and has hands and numbers that are clear to read. The clock also comes in a larger "teacher" size if you are planning to model more often in front of your child. My favorite feature of this product are the tiny windows you can close over the numerical display below. This works great for when your child (or you) sets the time by manipulating the hands and wants to predict the time before checking the answer. LoLo, who is only working on "O'Clock" and "30" times right now loves trying out the hands and shouting the answers himself before checking.
Learning Resources The Primary Time Teacher Junior 12-Hour Clock is a fantastic tool that I only wish was around when I was a child struggling to learn to tell time!