As I tried using regular .pdf worksheets in an interactive whiteboard page, I noticed the font was too small and too faint to be useful. These .pdf pages are intended to be "printed" to the pages of SMARTBoard Notebooks and then locked into position.
NOTE: Open the Notebook file you intend to use and minimize the window. Open the .pdf you would like to insert into your notebook and click on File, Print, Print to Notebook. When you maximize your notebook again, you should see the .pdf inserted as an object. For ease of use, lock the object in place. Now you should be able to work the problems on the page without your marks disappearing every time the scroll bar is touched.