"The Bus" (a.k.a. The Magic School Bus, "Bus" by Valerie and Fiona, and "Bussy" by William) is the common name of the anthropomorphic school bus that Ms. Frizzle's class and Liz ride on and goes on field trips and is the main character in the series. It is most often piloted by Ms. Frizzle, her sister Ms. Frizzle or Liz, but occasionally, one of the kids will take the wheel (like Ralphie in "Kicks Up a Storm" "Going Batty" and "Gets Lost in Space", Wanda in "Gets Lost in Space", Carlos in "Gets Ready, Set, Dough", and Tim and Phoebe in "Taking Flight") or it will take on a shape (such as an animal) that allows it to "drive" itself.
The Magic School Bus is somewhat based on a 1970s Ward International bus with fender skirts on the rear wheel, the front windshield being 2 different windows, and a grille spine down the center of the grille.
In the original series, The Magic School Bus was painted fully Walkerville yellow. In The Magic School Bus Rides Again, it is painted in the common North American School Bus yellow with black stripes.
It isn't really clear how The Magic School Bus works, but there are some hints in the TV series. We can see the how the fuel gets to the engine in "Revving Up". First of all, its magic seems to flow from several unusually named devices, like the shrinkerscope or the mesmerglober. The shrinkerscope serves mostly as an easy way to shrink and resize the bus at the will of Ms. Frizzle. It seems to have at least two varieties of the shrinkerscope, namely, the main one (as an internal part) and the porta-shrinker. At least the latter can't work when damp or wet, and if someone attempts to activate it in such conditions, the dew-dinger sounds.
The mesmerglober, on the other hand, is primarily concerned with changing the shape of The Magic School Bus. It changes it into whatever the class needs, be it a bus-marine, a spaceship, or a bus-igator.
In A Magic School Bus Halloween, The Magic School Bus is now a science laboratory but at the end, Ms. Frizzle as the old man restarts it while taking the 3 students back to Halloween Camp at the museum.
In the episode Making Magic, it pretty much reveals where the bus's magic comes from: a magic battery (Mag-Batt for short) and it runs on solar power with actual energy from the center in the sun, as well as true courage and perseverance as revealed by Fiona Frizzle herself.
- The Magic School Bus seems to have a deep caring for the students in Ms. Frizzle's class. This is displayed in Gets Ants in Its Pants when it is pouring with rain and it graciously offers Keesha the chance to get dry by getting in. She declines, arguing she "deserves" to get wet and the viewer can see The Magic School Bus pity her as she sits on a wet log.
- The Magic School Bus reveals to be sentient, mainly due to having eyes and a mouth. This is further in shown in Taking Flight when it gets angry at Liz for constantly making it crash when Tim and Phoebe were trying to save the rest of the class, in the opening when it looked a bit scared upon seeing an octopus in the neighborhood, and in Gets Lost in Space when it felt exhausted upon Janet overloading it with "proof" she went to all the planets of the Solar System. It is shown The Magic School Bus is incapable of talking, but it is capable of panting and coughing and the famous honking is used for talking as revealed in Rides Again. It's also unknown what gender The Magic School Bus is.
- The Magic School Bus has few modifications throughout the series, which include:
- Original Series:
- It had fender skirts covering its rear wheels.
- Rides Again:
- Its fender skirts are removed from the rear wheels, thus revealing its rear wheels.
- Back Antennae and roof hatch are added.
- On the back, it has two doors instead of one.
- Its bottom lip is a darker shade of silver than its top lip.
- Its headlight eyes turn light aqua.
- It now has one extra window on its sides.
- Original Series: