The aim of this series is to improve the student's ability to speak and write accurately, fluently and expressively. It contains 15 units corresponding to units in the coursebook. Both Third and Fourth Dimension can be used as free-standing coursebooks or combined to take students up to a level roughly equivalent to the First Certificate. The Fourth Dimension is intended for adult and young adult students who have been exposed to, but have not necessarily learnt, the "core" structures of English. It is designed to give them the practice they need in order to use English accurately and with confidence.