Jonathan not only has workbooks left to finish but he also was having a very hard time focusing on his work so we needed to find a solution. I did some brainstorming with my Mom and between our ideas this is the solution that has worked:
My kids are racing to get their schoolwork done each day. Each morning we start out with Jonathan and Mara reading through their Math lesson and doing their practice problems while Aaron reads aloud to me. For that we do not race. But then they all come to the living room and I say "On your Mark get set, GO!" and off they race to their desk and Jonathan does 10 Math problems (1/3 of his lesson), Mara does 12 problems (1/2 of her lesson) and Aaron does one page. Whoever gets done first can have 5 chocolate or butterscotch chips. We continue to race through the rest of their work.
I have divided their work into pretty short sections so the races go pretty fast. They do have to correct any problems they get wrong so they aren't hurrying to the point of not doing a good job. The races have simply helped them (Jonathan especially- the other two generally already did a pretty good job) to stay focused and concentrate.
We have all loved the result as now we are all done with schoolwork (except our fun read aloud learning books which we do year round after lunch) anytime from 10:30-11:30 and we are starting our workbook time around 9:15-9:30 (after we pray, sing, memorize and read a little). That really frees us up for the rest of the day to get other stuff done. We have always tried to get done before lunch (which can sometimes be at 1:30 pm) but this extra hour or two of time is very nice!
Anyway- for now racing with our schoolwork is working very well for us!