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 have most of the Level 1 books. They are a great introduction to science for little children. The only reason these don't get five stars is because a slightly bigger font size would have made these books excellent.