Helen Ball is co-author of the new Collins Core Maths resources. She is an ex-IT project manager who switched to maths teaching, rising to Head of Mathematics and teaching from KS3 through to KS5. She is an IGCSE and A-level examiner. Chris Pearce has an MA in maths and over 30 years’ teaching experience at secondary level through KS3 to KS5. Now a full-time author, education advisor and examiner, he has written many bestselling KS3 and KS4 materials for Collins.