When a burst pipe dashes Julie's plans for "The Wizard of Oz," Idina Menzel gives the Greenies a pep talk and inspires a wickedly good alternative.

The Greenies start working on the script for their mashup musical with help from Chris Colfer, who teaches them that words are important.

Josh Groban visits the theater for Julie's birthday and shows the Greenies how to sing from the heart -- and in perfect harmony.

When a disappointed Peri learns she'll be playing an ogre, Alec Baldwin reminds the Greenies that acting is all about pretending.

The Greenies hit the barre for a master class with married dancers Tiler Peck and Robert Fairchild, who've come to show them some ballet basics.

Sara Bareilles stops by to teach the Greenies how to make their own melodies. But combining music and lyrics takes serious teamwork.

The Greenies attempt a run-through, but their focus is on the fritz. Can improv expert Ellie Kemper shape their chaos into something amazing?

When Fizz asks master violinist Joshua Bell for musical guidance, the friends learn that playing an instrument takes tons of practice.

Julie sends in a clown -- professional showman Bill Irwin -- to help calm Riley's fears about being funny and teach the gang about circus arts.

When the percussion instruments they ordered go missing, the Greenies are forced to improvise with a little help from the cast of “Stomp.”

Special guest Tituss Burgess shows up with an array of colorful costumes that help the Greenies bring their characters to life.

The Greenies' first dress rehearsal is a mess rehearsal. Can guest director David Hyde Pierce help them sort things out before curtain call?

It's opening night, and the Greenies are ready to share what they've learned with a live audience -- including VIP patron Mrs. Edna Brightful!