Located on private property with permission of the church park committee. Please be aware every Tuesday night the boy scouts have their meeting/activities at the little schoolhouse, so it may be busy with muggles that night! There are also activities held in the bandshell/dining hall at various times throughout the year.
There is a small area in front of the schoolhouse to park or go to the church lot and take a nice stroll down to the schoolhouse.
This area is dear to my heart and thought it would be a great spot to place my first cache. I grew up just down the road and spent many hours up here exploring around the church and schoolhouse, shooting hoops and hanging with friends. Was it really 45+ years ago? A friend shared a photo of the class of 1901 that two of her grandfather's brothers were in. Now I don't feel quite as old… 
As to the name of the cache, I've collected marbles over the years and have great memories of playing marbles with my dad as a kid. I could always envision the kids at the old schoolhouse knuckling down in the dirt playing marbles and arguing if they were playing "keepsies" or not. So the name just seemed to fit.
And heck, who hasn't lost a few of their marbles over the years? 
The cache is a small lock tight container and is hidden away from the schoolhouse. There will be a special geocache marble in a little bag for the first find and whoever that is, I would love to see a picture!
You could do small trades and I'll probably drop a marble in once in a while. You will need a pen to log and again, the cache is not in or around the schoolhouse so please use the hint if you get stumped.
I hope you enjoy the area as much as I do and don't forget to watch out for muggles when activities are going on!
BYOP