The Truly Terrible Mistake, 4Hardcover, 3 April 2018

After getting a truly terrible grade, Penelope Kingston makes a plan to perfect her grades in the fourth book in the charming Penelope Perfect chapter book series.

Penelope Kingston has never, ever messed up on a test--until now. After this Truly Terrible Mistake, Penelope needs to make sure that she gets absolutely perfect grades from now on in every subject, including the dreaded drama class.

Luckily, Penelope is very good at organizing, so she figures she can be the director of the upcoming play. But can Penelope handle the naughtiest girl in class?

One thing's for sure: Penelope Kingston didn't get to be excellent at most things by being a quitter!