Cruel yearbook comments show Sam who's got his back, a favor he repays at graduation. Feelings for Izzie confuse Casey. Elsa asks Doug a key question.

Sam’s art assignment inspires an impromptu field trip. Casey navigates a fight with Izzie. Evan works hard for a second chance with Doug.

After a disastrous dinner with Paige's family, Sam makes amends at the school dance. Casey's fury at her mom affects her relationship with Evan.

Sam deals with a big disappointment, Casey clashes with Elsa over college plans, and a recurring dream vexes Doug.

A hard truth keeps Casey up at night. Sam experiences a rough season with Zahid -- and Paige. Elsa and Doug brace for their next chapter.

A rogue plan for Zahid leads to a last-minute mission for Sam, Casey, Paige and Abby. Meanwhile, Doug faces a major test and makes a pivotal choice.

Ignoring Casey's wishes, Elsa throws her a big birthday party, while Sam insists on following a decade-old birthday ritual. The bartender haunts Doug.

As Sam gets political with his art, Elsa and Doug explore a (not-so-normal) weekend away. Casey and Izzie re-examine their relationship.

As Casey reaches a crossroads, she finds herself questioning a lot of things. But in the meantime, she helps Sam get over a hurdle of his own.

Zahid teaches Sam to lie, while Elsa practices being honest. Evan helps Casey get over an embarrassment. A doctor visit forces Julia out of denial.

To prepare for college life, Sam sleeps over at Zahid's. Sam's $700 loss reunites Doug and Elsa with Arlo's parents, former friends of theirs.

As Paige makes a plan in the face of adversity, Sam awaits a crucial academic update. Elsa endures an uncomfortable encounter.

When a classmate shows interest in him, Sam makes a list of pros and cons to see whether she's girlfriend material. Casey gets a prestigious offer.

Casey and Evan take to the open road for a tense reunion. Back home, Sam and Zahid get ready to party, and Elsa bids farewell to the past.

While Sam and Casey face friendship dilemmas, Elsa uncovers a charming surprise, and Doug makes an unexpected decision.

Sam becomes rattled after Paige invades his bedroom. Casey visits Clayton Prep and gets a taste of what life away from her brother would be like.

Paige proposes having an autism-friendly school dance to the PTA. Sam makes preparations for losing his virginity. Doug and Julia help each other.

When Paige makes a confession to Sam, he creates a checklist to figure how he feels. Things with Nick suddenly get too real for Elsa.

Casey tells Izzie what Nate did. Sam tries to figure out which colleges to apply to. Doug discovers a need to educate first responders about autism.

Interested in having a girlfriend, Sam researches dating advice and puts it to the test. Meanwhile, his overprotective mom Elsa must learn to let go.

Sam's frustration at being unable to find a therapist and Casey's anxiety about going to a new school spark a blowup between the two.

In peer group, Sam realizes he needs to manage his own money. Doug gets advice from Megan on dealing with Elsa. Evan meets Casey's new friends.

Sam loses his portfolio for his art school application and panics. Megan gets flirty with Doug, who makes a decision about Elsa. Julia calls Miles.

Casey feels less than welcome at Clayton. Sam asks Paige to spell out the rules of their "casual relationship," while Doug sets boundaries with Elsa.

A peer group meeting leads Sam to an important decision. Detention with Izzie shows Casey they have more in common than she thought.