I dropped my the bike while I was using a loaner for my beginner MSF course, because my hubby told me not to use the rear brake... I was kind of mad at him. Illogical, but sometimes us women folk are that way. After passing the course, I found some empty dry pavement and practiced braking a lot. I was terrified, but determined. I taught myself to use the right amount of front/rear depending on conditions. I also tried a dirt bike which gave me a feel for a sliding rear tire. I locked up the rear brake about a year ago, didn't go down...That was a nice wake-up call.
After, four years of riding and learning everything I can, I'm feeling a bit more confident. My final opinion, because this was a problem for me. Teach her to use both brakes. Explain how the physics actually works. She is probably really smart and can get this.. I know it's scary to let her try. I figure my hubby is a great rider but a bad bad wife teacher.
Some part of our beings longs to join a band of brothers on a daring and intrepid quest. ~Carl Sagan