THEY travel in packs (成群), looking at GPS (全球定位系统) screens. Suddenly, “I found it!” one boy shouts, running away from the group. “Me too!” shouts another a moment later, until all six kids are crowded around a tree, pulling at a bottle painted like tree bark (树皮). It doesn’t look like much from the outside, but everyone gathers around and can’t wait to see what’s inside.