STEM content on simple machines and robotics meets play and compassion. A diverse group of children with varying skin tones and hair textures works with a robot to build a treehouse. A black girl emerges as the leader of the group, and it's her friend Robot who assists them. Robot lends a fantastic feel to the story, since illustrations make it look like something out of The Jetsons rather than a robot like those described in backmatter, but the things it introduces (a wedge, a wagon with wheels, screws, a hammer, a ladder, and a pulley) are immediately relevant and accessible to child readers learning about simple machines and other tools. Singsong text (set to the tune of "London Bridge" in the backmatter and on an accompanying CD, performed by Norma Joan Wright) shifts from the pragmatic to the emotional when, after resourceful Robot helps build the treehouse, it is stumped as to how to help a fretful dog get up to it. The children use emotional intelligence and say "Pet him in a gentle way, gentle way—it's been a long day" and successfully sooth the dog so it can join them in the treehouse as Robot departs. Throughout, illustrations highlight the key tools and steps in the building process, and the backmatter provides more comprehensive information about their functions. Likely to be a friend to STEM elementary educators. (Picture book. 5-7)