T.H.
pumpkin carving is always a huge hit! Also I did an apple craft a LONG time ago when I was a kid ;) that is pretty cute...
cut up a bunch of apples, not sure how many, but a lot (probably 2 apples/kid??). If you have a mandolin, use that cuz you need them kind of thin. Then put them in the oven to dry them out. Then we used cardboard rings (I think available at craft stores) and hot glued the apples to the rings to make autumn wreaths. It's really a project for all ages and the older kids can always help the younger kids or they can use Elmer's glue...it will probably work. Then we glued on a festive bow and a door hanger. They were really cute and I remember my mom hung it up for a long time. You could get some spray shalack and give them a nice coat after you're done.
There is always the traditional leaf rubbing activities, that is good for the younger kids.
Games could be sack races or getting bails of hay and making race tracks to have races of bikes, trikes, or the older kids could do wheelbarrow races?
You could also make a group scarecrow that is to be displayed in town somewhere. Or you could raffle it off maybe to earn some money for something?? All the kids could help with that. The little ones would probably love stuffing it and the older kids would probably like dressing it and making a face. Plus they could maybe bring clothes from home or something.
I think with ten kids you can really go crazy! It's such a small number...the only issue is such a wide range of ages!