Another sure-fire winner for math teachers and school libraries alike, this follow-up to *Great Estimations *(2006) recaps the basic estimation methods (eye-training, clump-counting, box-and-count) and gives readers several opportunities to practice them. But then the author gets tricky, mixing up the groups of objects with things of vastly different sizes, unevenly spreading them across a surface or irregularly layering them. Finally, readers will be challenged to use what they have learned to estimate length, height, weight, area and volume (in both U.S. customary and metric units). The “Hints” boxes at the bottom of each page give readers a starting point, as well as help with some of the mathematics involved in estimating large numbers of objects. Speech bubbles add some levity to a subject that children often find difficult, especially since there are no concrete “correct” answers (in either real life or in this text). Most importantly, the author’s note gives specific examples of the ways estimation skills are pivotal to many professions, giving readers extra motivation to push toward mastery. Don’t underestimate this one’s value. *(Informational picture book. 7-12)*