Aggers you might want to teach her the mouse zoom function.
Hold down either function key and scroll the mouse wheel forward to zoom. Scroll backwards to zoom out.
Also if you are on the keyboard, Ctrl+ will zoom in, Ctrl- will zoom out and Ctrl- (either 0 or * depending on the OS, browser, keyboard installed), will zoom you back to default.
I find most tablet users want a touchpad so they can pinch and stretch. Which is, to me, the most awkward and painful way of zooming on anything other than a tablet or a phone. I switch off all advanced functions on my touchpads so it would not help anyone using that over a mouse on my machines....
Just some thoughts.