Nope, there's no way to do that.
There is a workaround: in System Preferences > Mission Control, make sure "Automatically Rearrange Desktops" is checked. Then click the dock icons of the full screen apps in the order you want them.
For example, if you want Safari, iTunes and Mail to be in that order, then click Safari, then iTunes, then Mail in the dock, in that order.
I guess Apple thought this is better than dragging and dropping, it's way more fun and magical, and it keeps the kids busy as it takes ages to do.