I am sitting here after looking at mine. I would say it basically appears rigid and I would be afraid to push the top plate down, so there is very little flexibility, if any. I just rest my mouth on it, very lightly and gently. Then as i squeeze the handle, very slowly forcing the mouth open with the up aand down motion. One thing they told me to do it slowly, and then hold it open for the count of seven. Most of the pressure seems to be on the back teeth(or prosthesis) and I feel the stretching in my jaw. I just open until I begin to feel pain, count to seven and then release it. Did you Mom have someone demonstrate it? Does she have an obturator? Is doing these exercises with the obturator in?