Online Whiteboard resources
This is great site for a few interactive mathematics activities for Primary School.
There is addition, Thinking Skills and shapes and measures.
I used the perimeter resource above and found it very good.
You can decide on simple or compound shapes.
If you need another shape just click on the button and you get another shape.
I did have a problem trying to place the answer in to check.
Still a very nice resource for your classroom!