To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
We started lessons for our daughter, had her teacher buy the same book, and went to open the book for the first time, and we're missing pages 18-34 :( Totally disappointed. We paid nearly $20 for a book that's not compete!!!