We all know that our PDFs may need some tweaking for digital delivery. Sometimes the instructions are irrelevant, other times there are page numbers that might distract students-- the blemishes come in many forms. Fortunately, Classwork.com's Color Block tool works like a concealer to make your worksheet look good on the screen. 

To use the Color Block, click down on your activity or click and drag to draw a box. The Tools menu will pop up. Select 'Color Block' from the right column. Or, you can click "Insert" on your tool bar and choose Color Block from the Content Tools menu. If you do it this way, your cursor will turn into crosshairs, and you can draw your Color Block box. However you get there, it looks like this:

Draw Color Blocks wherever you would like things to be hidden on your assignment. 

On the Options bar (just below the tool bar), you can make adjustments such as change the fill color and border color of your Color Blocks. (Most times you'll just be using white with no border.)

Note: If there are already question types or other added interactions, they will need to be deleted in order to full cover up that portion of the activity.