Madison Wolfe as Barbara Thorson

Zoe Saldaña as Mrs. Mollé

Imogen Poots as Karen Thorson

Sydney Wade as Sophia

Rory Jackson as Taylor

Art Parkinson as Dave

Noel Clarke as Mr. Mollé

Jennifer Ehle as Mrs. Thorson

Ciara O'Callaghan as Theresa Tuzzo

John Boyle as Giant (voice)

Brandon Maher as Jock

Don Wycherley as Principal Marx

Amanda Stuart as School aide

Aideen Wylde as Mrs. Potts

Ben Carolan as Mophead

Sonya Kelly as Mrs. Laney