This book aims to prepare students for the GCE O Level Examinations. Each chapter of the book consists of: 1. Learning Objectives: Learning objectives of each chapter based on the latest syllabus are given in this section. Students should make sure that they are able to meet all the basic requirements of the objectives before they sit for the examinations. 2. Overview of the topic: This table gives students a concept map of the topic. It shows students the structural links between the sub-areas of each topic. 3. Key Points: This part features concise revision notes to help students concentrate on more important areas. All essential key points are presented to help students to consolidate their knowledge learnt in class. 4. Stop & Think (Challenging questions with solutions): For each sub-topic, challenging questions have been consolidated to check and evaluate student understanding. This ensures that doubts are better clarified before they proceed to the next section. 5. Exam Tips: Exam Tips in this book summarise all of student common mistakes, weaknesses and misconceptions shown in past examinations. Some important reminders for students are also listed in this section.