One way I do this, especially on a laptop with a smaller monitor, is to use Alt + Tab.
If you have the window with instructions open in one window, and the page that you are working on open in another, you can flip between screens with a simple Alt + Tab. A menu comes up with all of your open windows when you first hit Alt + Tab. You can continue hitting Tab while holding the Alt button until you get to the page you are looking for.
Try it out, I promise it won't hurt anything.
The menu looks like this.
