For the treehouse, help them put furniture in it, or little books, or other things that will 'make the house a home'.posted by lhall at 12:24 PM on May 24, 2007 Obstacle course.posted by cashman at 12:25 PM on May 24, 2007 A bamboo forest--fun to play in, AND lots of raw materials for building/making stuff.posted by MrMoonPie at 12:28 PM on May 24, 2007 I do not know what it is called, but my favori