down strong enough to produce a good sound, you might try having her be the teacher. you would play the same song, and not put your fingers down strong enough to make a good sound. ask her, the teacher, to help you make a good sound. you can guide her into telling you what to do better with your fingers.
i just did this today with a four-year-old student. we were working on monkey song on the a string, and my student had trouble holding her fingers down strong enough to produce a good sound. i put a little pressure on the finger and asked her if she felt the string 