Once Mike lets it slip that Axl is his favorite, Frankie's plans for the summer are thwarted. Axl is forced to attend summer school to re-take his English class. Brick attends to his summer tomato project while Sue does her best to engage Mike so she can proceed with her scrapbook.
Frankie's nostalgic summer plans go awry because of Mike's slip up. Axl is forced to attend summer school while Brick and Sue concentrate on summer projects of their own.
When Frankie is suddenly fired from Ehlert Motors, she embarks on a quest not to repeat mistakes from the past by taking any crummy job that comes her way, deciding to go instead to tech school to secure a real career. Meanwhile, school has begun and Axl is starting his Senior year in high school, Sophomore Sue takes on the task of mentoring new freshman Jenna, and Mike is upset with Brick when he can't be bothered to put his book down to meet some of Mike's friends after a softball game.
When Brick develops yet another quirky tic that begins to overshadow his whispering, Frankie and Mike are urged by the school therapist, Dr. Fulton (Dave Foley), to get him a small pet so that he can learn to bond with it, which in turn will help him bond with people. But when they present Brick with an ill-tempered bunny, the tiny animal teaches the Heck family the true meaning of evil. Meanwhile, as the Homecoming dance approaches, Axl finds himself dating cheerleaders Courtney and Debbie - but he doesn't know which one of them is actually his girlfriend - and Sue tries out for school mascot.
Trashy neighbor Rita Glossner returns and is about to rain fire upon the Heck household when she accuses Frankie of stealing her hose. Meanwhile, Sue takes a peek at Mike's paycheck and is so shocked at how little he makes that she decides to call off her first official road trip to Cincinnati for her school mascot duties in order to save money; and while Brick learns about the birds and bees in school, Axl shocks his little brother by explaining the whole process in graphic detail.
As Halloween approaches, the Hecks get quite the scare when Sue receives her learner's permit, and it's time for Frankie and Mike to teach her how to drive. But when a freaked-out Sue loses her nerve, she ends up running over Axl's foot, which could put an end to his high school football career and his hopes for a scholarship. Meanwhile Axl looks forward to voting in his first election, and Brick undergoes an unexpected transformation when he eats too much Halloween candy.
Frankie is made an example of in front of the entire class when she doesn't make a good impression on her first day of dental assisting school with no-nonsense teacher Mrs. Armwood. Meanwhile, because Axl's broken foot may end any chance of his receiving a college sports scholarship, Frankie and Mike insist that he up his grades and get himself a tutor; and Sue and Brick think they've stumbled upon an expensive item inside an old safe and try to get big bucks for it from a local pawn store employee.
Frankie tries to do a good deed for Thanksgiving by inviting a couple of Marines to celebrate the holiday with her family. But with Frankie's parents, Pat and Tag, constantly bickering, the good deed may not go unpunished. Meanwhile, while Axl grapples with his growing feelings for tutor Cassidy, he receives the good news that his foot is healed and he can play in the big game; Sue tries to track down the thief who has stolen the chicken head off of her school mascot uniform; and Brick becomes mesmerized by a book on the making of the film "Love Story".
Christmas doesn't seem so merry to Mike when he helps brother Rusty (Norm Macdonald) move some furniture into the Heck house garage and discovers that Rusty doesn't actually own the items. Meanwhile, Frankie hatches a plan to take a part time holiday job in a department store in order to get an employee discount to buy presents; Axl turns the garage with the stolen furniture into his own bachelor pad; and Reverend TimTom makes a bold choice by casting Brick in a holiday play and tasks an overly zealous Sue with baking cookies for the event.
As their 20th anniversary approaches, Frankie begins to think that Mike may be tiring of her company and is purposely trying to avoid her. Meanwhile, Sue frantically tries to coax Axl and Brick into helping her set up an anniversary party for their parents, and Brick falls into a non-responsive state when Axl tells him the ending of a book he's been waiting years to read.
Axl is shocked to discover that he and Sue are enrolled in the same Life Skills class. And things only get worse for the Ax-Man when he is assigned to work with his sister on a big class project. Meanwhile Brick's school therapist, Dr. Fulton, tries to teach him how to reach out to his fellow students in order to make some friends; and Frankie and Mike find themselves dealing with an unreasonable insurance company after they discover a tree branch has fallen and broken the windshield of Frankie's car.
Feeling guilty over not being able to spend enough quality time with each of their kids, Frankie and Mike decide to dedicate each day of a three-day weekend to one of their offspring. Unexpected revelations emerge when Axl takes them to a paintball range, Sue talks them into an exhausting itinerary consisting of 17 separate activities, and Brick tries to bring them to a "Planet Nowhere" sci-fi book convention.
Mike is upset with Frankie when he discovers that she set him up on an adult playdate with a new neighbor who shares the same interests. Meanwhile, when the school cheerleaders announce that they're taking over cheering for the wrestlers - thus putting Sue and her Wrestlerettes out of business - a determined Sue demands a cheer off; and Brick makes a lovesick Axl begin to question whether he's intellectually stimulating enough for his smart, new girlfriend.
While other kids begin receiving college acceptance letters and Axl still hasn't, Frankie and Mike begin to worry that their son's chances for a sports scholarship have passed him by. Meanwhile, Sue is determined to prove that smiling is contagious as a hypothesis for a school science project, and a relentless Brick begins pestering his parents for an iPad.
As Valentine's Day approaches, Axl takes Boss Co., with partners Sean and Darrin, to the next level by offering their services to help guys break up with their girlfriends. Meanwhile, Brick becomes upset with Frankie when he discovers that she has thrown out all of the school artwork he has made over the years, Sue is thrilled when ex-boyfriend Matt invites her to the school's Valentine's Day dance, and Mike accidentally sends a romantic text meant for Frankie to a co-worker at the quarry.
As Frankie prepares for her upcoming annual tradition of watching the Oscars on TV, she becomes concerned when Brick informs her that he's taking a three-day school bus trip to Chicago, and she worries that his unique quirkiness could lead him to become separated from the group. Meanwhile, Sue wants to find out if Axl's friend, Darrin, has feelings for her.
After accidentally breaking the family room window, Axl, Sue and Brick decide to band together and place the blame on the neighborhood bad seed Glossner children. But Frankie and Mike know that the kids aren't being truthful and put together a wheel of pain, in which the kids must spin the wheel and land on a consequence, hoping that one of them will break down and confess - which puts Sue's "Sue-weet 16 Party" at risk. Meanwhile, Frankie needs to please her no-nonsense dental assisting school teacher, Mrs. Armwood, in order to obtain a prime dental rotation spot.
Frankie's sister, Janet, comes to the rescue and offers to help run the Heck household while Frankie studies for her dental assisting school finals. But the sheer amount of disorganization in the house throws perfectionist Janet for a loop. Meanwhile, when Cassidy's ex-boyfriend pays an unexpected visit from college, Axl tries to take the high road and not act like a jealous boyfriend; and Sue wants to legally change her middle name - which is also Sue - in order to have a normal name on her driver's license.
Frankie can't hide her disappointment over whom "The Bachelor" chooses to marry and ends up moping around the house for days about it; Mike tries to toughen Sue up when she joins the school's tennis team and continually compliments her opponents during their matches; and Axl and Cassidy try to figure out where their relationship stands after their big fight.
After successfully graduating from dental assisting school, Frankie attempts to interview for a job but discovers that, when asked about herself, she doesn't quite know how to describe who she is. Meanwhile, when Axl gets his band their first paying gig at the Orson Dollar Days, Sue becomes a 'Yoko' to boyfriend Darrin's 'John' and begins to offer unwanted advice to the group; and when Brick informs Frankie and Mike that he has joined the Prairie Scouts, Mike ends up reluctantly having to lead his quirky troop's camping trip. Jack McBrayer guest stars as Dr. Goodwin, who interviews Frankie for a possible job.
After discovering that Sue's life, as defined on Facebook, is pretty pathetic, Frankie creates an online alias (or two or three) and tries to make her daughter as popular as possible. Meanwhile, after reading Tuesdays with Morrie, Frankie's healthy dad, Tag, coerces Mike into listening to his long-winded life stories on a weekly basis; and Axl and Brick attempt to garner interest in getting a bunch of baby bunnies and kittens adopted by producing a viral video starring the animals in a James Bond knockoff.
As Mother's Day approaches, Frankie wants to ensure that Mike gets her something she actually wants for a gift and informs all of the kids of her wish so that at least one of them will clue in a clueless Mike. Meanwhile, Sue asks Reverend TimTom for advice when she begins to resent her friends' happiness over getting their driver's licenses after she has repeatedly failed the test, and Cassidy stuns Axl with some bad news during the prom.
While waiting in line at the power company to pay a late bill and dressed in her lab coat for her new dental assisting job, people mistake Frankie for a doctor and let her cut in front of them so that she can finish her business quickly and get back to saving lives. But when one of those people shows up at Dr. Goodwin's office for a dental checkup, Frankie tries to keep up the charade, which leaves her new employer completely perplexed. Meanwhile, Axl discovers that Sue has a perfect attendance record at school and convinces her to ditch a day to live life on the edge; Dr. Fulton tries to find out why Brick is so opposed to going to middle school; and Mike and Axl's fishing trip takes a turn for the worse when a distraction causes Mike to crash the boat he's towing, wedging it into a ditch.
As graduation day approaches, tension begins to build between Frankie and Axl when he ignores her requests for answers about the graduation party she's planning for his special day. Meanwhile, Sue hopes that the sixth time's the charm as she once again attempts to pass her driver's test; and during his final days of elementary school, a forgetful Brick is reminded by Vice Principal Dunlap that he's the class historian and is responsible for putting together a slideshow highlighting the last four years of school for the school assembly.