Children's Mental Models of Recursive Logo Programs

Children who had a year of Logo programming experience were asked to think-aloud about what brief Logo recursive programs will do, and then to predict with a hand-simulation of the programs what the Logo graphics turtle will draw when the program is executed. If discrepancies arose in this last phase, children were asked to explain them. A prevalent but misguided “looping” interpretation of Logo recursion was identified, and this robust mental model persisted even in the face of contradiction between what the program did when executed and the child's predictions for what it would do.