Twenty Is Too Many

The irrepressible and mathematically driven guinea pigs are back, and the teaching of subtraction is the better for it. This time, the roly-poly rodents start out on a ship that threatens to sink if the occupancy isn't reduced from 20. Fortunately, 10 guinea pigs go for a swim right off the bat: ""Twenty sinking guinea pigs minus ten diving guinea pigs leaves ten floating guinea pigs."" Duke next reduces her group one by one, as a story unfolds the characters' arrival at a desert island, where they discover a hidden treasure and the joys of surfing. As in One Guinea Pig Is Not Enough, Duke plants oversize, colorful numerals prominently in each airy, rollicking double-page spread, and the guinea pigs comically capitalize on their presence (for the spread illustrating 5-1=4, the boat is shown lashed to the numeral four). The appropriate equation appears in the lower-right corner of the spread when each stage of subtraction is completed. Although Duke's last words to her audience are ""And one can be fun,"" the final, textless illustration shows all the subtracted guinea pigs exuberantly reunited on the rather tiny island. Will they try multiplying next? Ages 3-7. (July)