This website provides great student whiteboard activities for elapsed time. There are two clocks that are completely changeable so that you can ask students what the elapsed time is. I use the dice frequently because it provides completely random times. You can hide one clock and then give how many hours before or after that specific time and now your students have to either draw the time they calculate it to be and then unhide the clock so students can verify their calculations.
You can also hit the question button and it will pop up a word problem involving elapsed time. This is very digital whiteboard friendly, with large buttons and the ability to manipulate it all without ever going back to your computer.
