Each chapter in the Common Core Practice book explores a Common Core State Standard domain. For each content area. individual standards are then available with 10-20 practice questions per standard. Each question includes a detailed answer explanation in the answer key. The Lumos Online Workbooks consist of hundreds of grade appropriate questions based on the . Students will get instant feedback and can review their answers anytime. Each student's answers and progress can be reviewed by parents and educators to reinforce the learning experience.