Time Train

When Miss Pym's class boards the Rocky Mountain Unlimited on a trip to learn ``all about dinosaurs,'' a seemingly ordinary outing takes a wildly unexpected turn. Fleischman's understated text sets up the illustrations as punch lines in this tongue-in-cheek time-travel adventure. Each stop offers bizarre views as the train carries the youngsters closer to their destination: the sight of a woolly mammoth across the snow-covered tundra signals ``that the weather had changed''; giant insects zooming through the train indicate that things ``had warmed up a bit.'' Only Miss Pym's continually startled expression belies the unusualness of the experience as the students make scrambled (dinosaur) eggs and romp with the behemoths on the beach. The larger-than-life train illustrations bring to mind Van Allsburg's The Polar Express , although Ewart's palette, with its vivid blues, greens and golds, has an otherworldly glow. Ages 5-9. (Sept.)