If you are already using iPads or iPods in your classroom then these clocks become interactive and work great with Educreations app (or any interactive whiteboard app) and Apple TV through AirPlay.
This is how I use it in my 3rd grade math resource room. I simply instant message the PDF file has an image and have the kids save it to their camera roll. They then pull up the picture using Educreations app. I then ask them to draw a specific time in one color. Then I ask them a couple elapsed time questions and they draw those times in different colors. They record their answer and share it in our class account in Educreations. Then we share as a class through AirPlay using Apple TV.
Here is one example.
Look for more PDF's soon that work great with iPads and iPods using AirPaly.