Essential Mathematics for the Australian Curriculum Fourth Edition Interactive Textbook is an online version of the student book that delivers a host of interactive features to enhance the teaching and learning experience. The Interactive Textbook is available as a calendar-year subscription. Your subscription term is defined as follows: if activation occurs between January and July of this year, subscription concludes on 31 December this year. If activation occurs between August and December of this year, subscription concludes on 31 December the following year. Digital resources are expressly available for personal use only.