The white paper usually gets stacked by the printer so the blank side can be used for printing non-important things.
Sometimes it is drawn on. Or turned into a paper airplane. Or a hat. Or a sword. Whatever.
Cutting standard-sized paper into quarters and securing the stack with a binder clip makes the perfect size notepad to put by the phone. It can lay flat or be hung up by the clip.
You can also make multicolored paper chains, blank side facing out. I suggest using a paper cutter rather than scissors to make the strips. Forming the chain can keep a kid busy for ages.