As others said, this episode is out of sequence.
The story was flat, though Ward and June helped to bring some life into it, June forcing Ward to be accountable for his mistake, though it is frustrating to see how out of step it is with the series time line.
Wally and Beaver had already graduated in earlier episodes, and per the previous episode Beaver was supposed to be away and touring the country all summer with his friends, and Wally no doubt already getting ready to be "up at State," so it did not make sense to see Beaver back at Grant Avenue Elementary - and suddenly acting about 2 years younger, with his hair a mess and worrying about being a poor citizen, and Wally coming home from school with his books under his arm.
I've dreaded this episode every time it comes around - why can't Universal shuffle the episode deck or shelve it entirely?
I hope someone from Universal (or at least the actors or their agents) will read this and ask this episode be pushed back to the beginning or middle of Season 6 (by the way the boys were dressed when they were walking to school, it was supposed to be Fall or Winter).
It's a shame, because a weak episode like this brings down the rest of the series, and since it's the penultimate episode, it leaves many confused over the disrupted time line. Like they say, most people judge things on a first - and last - impression. From what I once read on the show's Facebook fan page, the episode was originally not meant to be the next to last but was reordered when a mutual decision was made not to continue the series.