As soon as the kids came to the door, my son directed them to pick a car, open it up, place the pieces in their bowl, and then start building.
They all were into making their cars. Give 8 year olds a Lego set and you get a quiet room!!!
After they finished the cars, they got to race them on a Lego Race track I made. I just used two pieces of thick poster board and designed a road with construction paper and graphics I found online.
I put the board on a plastic table with one side of the legs set up for the ramp. They spent 45 minutes just playing with this and racing their cars. It was a hit!!!
Here they are in action: