Playing Marco Polo

"Marco Polo" is a great sound game to play with a group of children, or a mixture of children and adults. It's similar to "hide-and-go-seek" except that you use sound rather than sight to find everyone.
With young children, the best place to play is outside in an enclosed area, but you can play anywhere, even inside the house. The "seeker" looks for the "hiders" by calling out "Marco!"
Whenever the seeker calls "Marco!" the hiders have to respond by calling out "Polo!" Can the seeker find all the hiders by listening?
This is a challenging game for young children. Little seekers may need to open their eyes frequently to get their bearings.