Einstein is Mildred's pet tortoise. He was originally called Speedy and was one of the animals she tried her animal-speaking spell, her third year holiday project, on. After saying he dislikes the ironic name "Speedy" Mildred renames him "Einstein". After discovering that Einstein can still speak and overheard the conversation betweenEthel and Mildred about the project, and that Einstein only has one more day before the spell wears off and he becomes mute forever, Ethel orders Drusilla to get dressed again and hide Einstein in the hollow pine tree outside the school gates for two days to be on the safe side. Cyril the toad tells Mildred where he is and she retrieves him. It is Einstein who tells Miss Cackle and Miss Hardbroom the truth about Ethel knocking Mildred's bag out of the tree, turning her pot into snakes, and stealing her project and passing it off as her own.