To impress his teacher and friends, Beaver fabricates owning a pet parrot to bring to the school pet fair but finds out that he can't afford to buy one when he goes to the pet store to make good on his claim.
Beaver finds it a challenge to write a fifty word composition for a school assignment about his mother's life as a girl, especially when his classmates' mothers' lives seem much more exciting than June's.
When Beaver's teacher Miss Landers assigns the class a book to read Ward suggests Ivanhoe, one of his favorite boyhood books. Impressed by the tale of knighthood, Beaver forms his own knight club and sets out to defend his neighborhood.
Over breakfast on the last day of school before summer vacation, Beaver and Wally sneak a peek at the gift June bought for Beaver to give to his teacher. The embarrassed boys find a lacy slip and, not knowing that the department store made a mistake and that his gift was supposed to be handkerchiefs, Beaver must decide whether to give Miss Landers the slip or nothing at all.
When Wally and Eddie coach Beaver's summer football team and give them a secret play to use against the opposing team, Beaver finds out that the best way to keep a secret is to not tell it...to anyone!
Ward and June are concerned when they discover that Beaver's visiting friend Chopper has divorced parents but soon see that Chopper's own experience will serve as Beaver's best lesson on this life changing event.
Beaver's slightly exaggerated story about rescuing an abandoned canoe while fishing with Wally takes on a life of its own while passing through the school grapevine and Beaver finds that not being completely truthful can have disastrous results.
Beaver proudly takes his friends Whitey and Gilbert on a picnic at the lake to see Wally in his first day as a lifeguard, not knowing that a new law forbidding anyone under age 18 from filling the position has forced Wally to work as a snack vendor instead. When he sees Wally in a floppy hat peddling hot dogs instead of sitting importantly on a stand in a lifeguard uniform, an embarrassed Beaver wants to go home before anyone else finds out.
Lumpy Rutherford embarrasses Beaver, calling him 'Freckles' in front of his friends and Beaver tries various ways to get rid of the offending spots. While Ward and June try to convince their son that what's important is not what he looks like but what kind of person he is, in the end, Beaver finds his own support from an unlikely place.
Beaver sells raffle tickets to benefit the new hospital and hopes that one of his own will win him a Hawaiian vacation or a sports car. When obnoxious Eddie Haskell teases that Beaver's parents would never allow him to keep a top prize and would most likely use it themselves, Beaver refuses to believe. But when one of Beaver's tickets is a winner will Eddie's dire prediction come true?
Eddie Haskell boasts about going steady with popular Caroline Shuster but Wally hears Caroline tell her girlfriends that she thinks Eddie is a creep and must decide how to break the bad news to his best friend.
Ward is concerned that Beaver's attitude toward his schoolwork will jeopardize his future and when the school principal announces that Beaver's class will be given an intelligence test Beaver worries that the results of the test will not only prove his father right but show that he's too 'dumb' to succeed.
To impress pretty, out-of town girl Kitty, Wally writes letters to her exaggerating his family's wealth and importance; but he must later eat his words when Ward and June tell Wally that he will be taking Kitty to the country club dance.
Ward and June leave Wally in charge at home and all is well until neighbor Mrs. Murdock drops by and asks Wally to take her son, Chuckie, to buy new shoes. But Wally goes ice skating with Eddie Haskell instead and turns little Chuckie over to Beaver. When Beaver loses Chuckie in the shoe store, Wally soon learns an important lesson in responsibility.
June attends a meeting at Beaver's school where teacher Miss Landers confides that several items have recently disappeared from student lockers; and when June finds the same items under Beaver's bed she worries that Beaver may be the thief. Ward questions Beaver and finds out that Beaver was given the items by another boy, Kenneth, but Kenneth denies everything and Beaver must find out why.
While emptying the trash, Beaver finds a circular that Ward discarded offering a free trial for an expensive new accordion. With a push from troublemaker Eddie, Beaver secretly sends in the order form, believing that he can play with the instrument and return it within the 5-day free trial period. But, as usual, things don't always go as planned.