Rondi is a background character in Mrs. Jewls' class who is usually seen brushing her teeth. She also has a notably dangerous sweet tooth for cake. Rondi was told by everyone that she had "cute" front teeth when she didn't have any. In the first book, Sideways Stories From Wayside School, Rondi bit Louis the Yard Teacher due to him telling her she had "cute" front teeth. In the second book, Wayside School Is Falling Down, Rondi grows two new front teeth and she decides to keep them, as they are excellent for bitting carrots. In the books Rondi is Allison's best friend. She is usually always grinning, but sometimes changes her expression based on the circumstances.
Rondi is a rather obese girl. She generally wears a light blue blouse with an orange collar. She also always wears round spectacles, and she has some freckles on her cheeks. She has brown hair in the cartoon, whereas in the books,it's blonde.