Getting children to do chores

Have you ever noticed getting children to do chores is kind of like pulling teeth with out any anesthetic. As I go around and sign out chores I usually hear but I did not make the mess. Why doesn't so and so have to do it. Today we tried a new thing everyone picked their own chores. I thought for sure this would work, boy was I wrong. my 9 year old decided that he would clean up the entry way which is usually give to the 4 year old but we said okay if you are willing to do it then you can have it. This was his way of going and reading a book in the entry way. So far out of 8 kids well only 7 had to do chore the baby did not have to only the three youngest did them. They are 2,4 and 5. the other kids who are 7,9,10, and almost 12 have not finished. Well we will see what happens at bed time when Mommy goes and collects everything that is left out for my bright new idea. On Saturday we will have a chore action were anyone can buy anything I have collected, all it will cost is chores. The highest bidder get the item as soon as they complete the chores.