(Strip Number 1210, Original Publication Date, 9 October 1987)
Panel 1: We find ourselves watching Lizzie yell over the back fence to Richard that she's ignoring him.
Panel 2: She then bellows that if he talks to her, she isn't going to talk to him and she's going to stay on her side of the fence and not play with him or anything.
Panel 3: Since the noise harshed Elly's mellow and reminded her that her life is blighted by small children, she rushes out to ask what Lizzie thinks she's doing. Lizzie tells her she did what she said.
Panel 4: When she says that she's ignoring Richard, the seeming paradox baffles Elly because we're dealing with a moron parent here.
Summary: This is because she's forgotten what it's like to think "How is he gonna know I'm ignoring him unless I tell him?" She can whine about that not making sense all she likes but this is how kids think and she's just gotta deal with that.