Look at this wonderful site I just came across! There are wonderful activities that can be easily projected onto the interactive white board to enhance instruction.
This is the activity I found first was when I was searching for some base ten activities for my firsties. As pictured below, it will automatically give the kids a number to build. In this example, "make 33 blocks." They have to click and drag the correct number of rods (tens) and units (ones) to the pad to make the given amount. It keeps track of how many they've added, follows the amount on the ruler, and models it in the hundreds, tens, ones cups on the bottom left. AWESOME!
They love using the hands on manipulatives but this site will give them practice in math centers, too. They're going to love it!! :)