When Isadora's teacher announces the class are having a maths test on Monday, Isadora gets a nervous feeling in her tummy. She really doesn't like tests . . . or maths!Maybe, Isadora could pretend to be ill so she can stay at home instead? Isadora calls her naughty cousin Mirabelle for help and she gives her a spell that will help Isadora get out of the test.To Isadora's delight, it works! But between a potion mishap and magic pox fluffballs bouncing around all over the place, Isadora starts feeling a bit guilty. Luckily, her mum is on hand to help set things right and together they come up with a new, magical way to say goodbye to the magic pox and even make revising for the maths test fun!