Book report objectives tell the reader what the book is about. Another purpose of an objective could be to encourage readers to take action after reading your report. For example, do you want people to purchase a product? Believe a certain way? Write their Congressman or Congresswoman? Vote a certain way? Perhaps you want to educate people on a certain topic.
Book report objectives can take the form of a question which you will answer in your paper. Right after posing the objective as a question, answer the question in a few sentences and then expand your answer throughout your paper. Another format for book report objectives is taking on a position with which most people would disagree. In the paper, provide supporting evidence for your position.
Focus on one point in your objective and expand on that one point in your paper. Make your objective specific. It is impossible, for example, to tackle world peace in one paper. Instead, take a position on a political party in one country. Explain why you feel your position is the best position. Provide evidence. Give statistics.
Keep in mind the classification of the book you are reporting on. Is it a history book? Perhaps it is an autobiography or a biography. Is the book about psychology or philosophy? If the book is on philosophy in a certain country, you would take a position on a belief by one philosopher in that country. The table of contents of the book will show you what points to focus on to support your objective.