The title says it all: from ``12 crocodiles...carpooling'' (unequally divided among three cars for extra arithmetic practice) to ``2 whales...watching for polluters'' and ``1 elephant...enjoying the earth,'' sensible suggestions for protecting the environment are dramatized in humorous spreads featuring animal characters—tigers turning off faucets, turtles taking cans home from the beach, rhinos using rechargeable batteries. All are practices young people can adopt or urge on adults. The author's simply rendered art is as open and cheery as a sunny day; she appends several fact-filled pages amplifying the basics offered earlier with how (e.g., identifying plastic recycling codes) and why (why fluorescent bulbs are preferable to incandescent). The serious message is delivered with an admirably light touch; and it's a good counting book, too. (Picture book. 4-8)