For the Walkerville space capsule, Ms. Frizzle's class has to put in something on air. Keesha brings an "empty" pickle jar though, as she explains, "It's not empty; it's filled with air." The rest of the class believes this is extremely pathetic and Ms. Frizzle "accidentally" gets the entire class stuck inside the pickle jar. Conveniently, they have to use air to get out of the jar in time for the space capsule's liftoff. Carmen makes a cameo, since she did not appear with Ms. Frizzle and her class.