|Occupation||History teacher at Downtown City High|
|Debut||Bakers and Fakers|
|Voiced by||Kathleen Barr|
Robinnia Amster, usually addressed as Ms. Amster, is Downtown City Junior High's history teacher. She is Bob Barish's love interest. She is originally from Scotland, which is apparent from her Scottish accent.
In Bakers and Fakers, she came into Mrs. Mondt's class accompanied by Bob Barish to inform the students about the Ultimate Outrageous Cake Competition. The winning team would get half a grade worth of extra credit at both Home Ec. and History.
During the competition, she complimented Mr. Barish's decisive attitude upon declining Blythe's request for more time before the start. Mr. Barish also set out to protect Ms. Amster from falling eggs, dropped by Zoe to help Buttercream not be seen.
Both teachers were delighted while tasting the cakes they would judge. She jumped into Mr. Barish's arms screaming when the cake of Brittany and Whittany Biskit scared everyone, prompting the teachers to announce Team Youngmee the winner.
She later appeared giving class in The Secret Recipe, at the end of Young Entrepreneurs Week. Youngmee prepared a presentation of her own product, Youngmee's Tasty Pet Treats. Ms. Amster was so impressed by Youngmee's presentation that she encouraged her to make it a real product.