Sesame Street Mecha Builders, Can't Stop The Martians / The Best Nest Test

A giant pie meant to stop an asteroid is eaten by Mechas and friends. At the museum, Singing Stone Heads sneeze instead of singing.

Ranger Nat and Mecha Abby get stuck in a crevice. Zee's rocket launch goes wrong when the launchpad breaks and the rocket lands on a farm.

A boulder rolls toward the museum, and Mechas help stabilize it. On Food Day, they fix a banana split statue with a missing banana.

A magnet crane sucks up all metal, including Mechas. Roof's egg delivery is disrupted when a train can't stop at the station.

Hero Day ends with a ripped projector screen. An ice slide melts in the park, making things slippery for Pretty Big City.

Chickens won't roll at the farm race. Ranger Nat's telescope falls off a cliff just as he's ready to see Pinecone's Comet.

Books go missing during the citywide read. A factory spews sticky slime, causing chaos in Pretty Big City.

Ranger Nat finds a treasure map but can't read it. Zee's mobile breaks down inside a corn maze during setup.

A broken windmill stops power at Sunny Field Farm. Izzy and Timmy struggle to build a bird caller for Grandma.

MacBarm's chicken food spills from his truck. Grandma and her twin try to recreate their zip-line act, but it no longer exists.

Berta needs a photo of the mysterious Whatsacallit. Nat gets lost in the woods while leading a hike as the sun sets.

Zee's giant croquet decorations won't fit on the farm. Mechas must place a sphere atop a skyscraper before the ribbon-cutting.

Moobert grows giant and needs a big shelter. Nat's kite blows away, so Mechas and Timmy build a new one to find it.

Martians break a bridge needed for a train to cross. Zee Mobile counts chickens but keeps crashing into the barn door.

Grandma and Timmy try stone carving for an art show. Nat finds a Big-Footed Cave Bird that can't return home.

Lloyd's testing a wind-up powered go-cart, but a problem arises when it keeps running out of energy. Sif's coming in for a landing at the rocket launch site - until her rocket is pushed off course by a satellite!

Lloyd is selling silly hats at the factory, but when the hat machine malfunctions, it starts raining silly hats on Pretty Big City! Zee makes a giant rocket ship in a bottle, but things take a turn when he gets stuck inside!

It's MacBarm's day off, and Zee takes over harvesting with his Zee mobile, but when it breaks, the work still needs to be done. Ranger Nat is bringing a playhouse on the train for Timmy and Izzy, but it won't fit through the tunnel!

The Martians are headed to Pretty Big City but find themselves in need of help. Zee needs to communicate with Sif in outer space, but can't because a bird has made its home on top of the satellite dish!

Panic erupts in Pretty Big City when the big clock breaks and no one is able to tell what time it is. Zee is showing off his inventions at his rocket-powered show, including his latest creation, a rocket-powered Ferris wheel.

Zee's new drone accidentally doubles as a cow caller, and the cows keep leaving the farm to go see it. But how? Marwyn attempts to make Pretty Big City's largest cookie, but to do so, he'll need a lot of help.

It's Halloween, and everything is set for the Zee Mobile to pull the haunted hayride. Timmy can't wait to trick or treat as a Mecha T-Rex, but his Halloween is almost ruined when he can't reach the arms of his costume.

The Martians want to help Lloyd deliver packages, but keep breaking them when they drop them from up high. MacBarm and Zee built a slide that sends people all the way across the farm.

Izzy and Timmy go to dig up treasure at the top of Lawrence Pinecone's Statue's shadow, only to find that nothing's there! The mysterious 'Pretty Big Thing' is scaring the people of Pretty Big City from going to work, but what is it?

When the ornaments on the Pretty Big City tree break, the Mechas must build new ones and save the holidays. It's time for Zee and MacBarm's gift exchange, but the snowman scarecrow Zee made for MacBarm keeps blowing away!

Zee's super sticky slime spills on Zee and MacBarm, leaving them stuck together. When Marwyn runs out of ice, the Martians send a giant hunk of ice. All goes well until the ice starts sliding towards the skyscraper!