The keyboard popup problem is being worked in bug 497381. Kids can pull equations from websites or type in their own. In fact most laptops dont.
Vintage Educational Keyboard Multiplication Machine Push Magic Math Practice.
A better thread for this is here with a workaround involving the --disable-usb-keyboard-detect flag See. While this is a serious limitation multi-level formulas are not always needed and even when they are needed proper math symbols still look better than improvised ASCII approximations. Math teachers know that typing math notation in Google Docs takes a bit of work. Ctrl X cuts the highlighted area and store it on your clipboard.