I came across a comment on the Internet that made me think the issue might have something to do with constraints. I opened up the scene afresh, and found that the object named Suzanne.003 had a constraint attached to it. I deleted the constraint, and performed the parent operation again. Now the child object moves with the parent, as in the tutorial video. I don’t quite know what constraints are yet, but I see that I will be learning about them in a future lesson.