The contents of the box in the precondition should read as follows:
[a picture of a right side wall | a picture of a puppy walking right | a picture of a puppy walking left | a sensor showing the value 50]
That is, the second hole of the box with the precondition should contain a picture of the puppy walking right (not left).
p. 254:
The third sentence in the third paragraph should read as follows:
In total, the six groups of children created eight games.