We have been utilizing the workbox system and I am timing her on each grammar section and it worked great. We got all the boxes done and had only a moment or two of whining which was due to frustration.
Some privileges had been lost earlier in the week due to taking too long and attitude so I wrote what her goals were for the day on the board and had her read them before starting. I told her that she can earn back what she lost by having a good attitude and not taking too long and it worked!
I think I will do that every day-set her goals and then tell her it is up to her whether she keeps privileges or loses them.