There's No Time for Love, Charlie Brown (1973)

Most of the Peanuts gang is having trouble at school, but none more than Charlie Brown. In fact, he is told that he needs an "A" on a field trip report on an art museum or he will fail his grade. Unfortunately, Peppermint Patty, over-tired by Marcie waking her up at 4:00 in the morning, inadvertently distracts Charlie Brown and his sister from their group and they all mistake a neighboring supermarket for the art museum. Even as they try to understand why all the displays are for sale so cheaply, Patty's weariness and her own ambivalent feelings about Chuck causes her to blurt out some hurtful comments about him. Now, Charlie Brown is going to have to realize his basic mistake in his report, while Marcie and Peppermint Patty search for a way of making amends to the boy they both secretly like in their own way.