"Gets Charged" is the tenth episode of season four and the forty-ninth episode overall of the animated children's series The Magic School Bus. It originally aired on November 15th, 1997.
It's Valentine's Day and the class is selling light bulbs. When they stop at Ms. Frizzle's house to sell her one, they find that her battery-operated doorbell doesn't work. While looking for her to tell her the doorbell is broken, Wanda overhears her talking on the telephone. When Ms. Frizzle calls the caller and states that she would love for the caller to "ring her bell". Wanda is convinced that Ms. Frizzle has a secret Valentine of her own and tells the class that they should fix her doorbell. Just then, Liz opens the front door and the class enters their teacher's house. Inside, they realize that everything in the house runs on batteries. Ms. Frizzle invites her class inside her bedroom and offers them a pair of specs to see that the top of Ms. Frizzle's hair is red and the balloon rubbed against it is blue. Ms. Frizzle explains that it's all done by the electrical charges that can only be seen through the specs each of the students is wearing. She also explains that two kids of charges work together, only for the rubbing to get pulled apart once Ms. Frizzle rubs her hair with the balloon, and sparks fly once blue and red charges join back together again.
After learning about the charges, the class leaves to fix the doorbell while Ms. Frizzle gets ready for her "big connection". They get Liz to go inside the bus to fix the doorbell while Wanda stays to look out for Ms. Frizzle with a walkie talkie. The bus, however, gets caught inside the heart-shaped light bulb.
The bus continues to fly inside the light bulb and Wanda tells the class that they could figure out how to fix the doorbell by getting inside one of the wires, which the class complies to. They come across a plethora of electric charges inside the wire and compare it to a current in the river. The bus then enters the skinny wire called the filament, which makes the light bulb glow. They end up inside the battery and get pulled along with the blue charges right before exiting the battery and entering the other wire of the bulb called the electrical circuit. Wanda then learns that the battery is what makes the charges work. When Ms. Frizzle walk to the garage, Wanda attempts to turn off the light bulb and accidentally removes the wire of the bulb. The class inside the bus realizes that even when the moving has stopped, the electric charges are still dispersed. Wanda then learns Ms. Frizzle's phrase, "When there's no flow, there's no go, and it's no glow" and continuously connects and disconnects the wire to demonstrate this. To keep Ms. Frizzle's lover from leaving her due to not being able to activate the doorbell, Liz uses the bus to exit out of the light bulb and the class, still in miniature size, attempt to help Wanda fix the doorbell by entering the wire of the doorbell. They notice that the charges aren't moving and exit the bus to search for the obstacle that's keeping the flow from penetrating. They finally discover that the wire is disconnected and Ralphie ends up dangling from the edge after nearly falling down as Ms. Frizzle arrives at her front door.
As the teacher enters the house, Ralphie manages to climb back inside the wire and Wanda finds the disconnections of the wire between the motor and the battery. Wanda then enters the house and obtains tin foil. She returns to the front porch and wraps it around the wire. The class enters the bus and Wanda activates the doorbell, which finally works. The bus exits the wire and the rest of the class exits the bus to find that Ms. Frizzle is nowhere in sight. So they search for her in the garage to find that the battery to open the garage door is worn out. So Liz uses the bus to transform it into a battery and the garage door opens, only for the class to find that it is empty inside. When they hear the doorbell, they run to the front porch and find Ms. Frizzle with an electrician named Mr. Amper. The class also learns that Ms. Frizzle knew the doorbell was broken and called Mr. Amper to fix it. The latter is impressed of the class' work and Ms. Frizzle connects the wires of her doorbell to activate the lights around her house, along with the light bulbs around Mr. Amper's truck.