Amazon calculates a product’s star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers, and factors that establish reviewer trustworthiness.
It is the required text for my son's online school program. It was purchased as an accompaniment to the text and was beneficial in his studies. It has served him well and he has now completed the course.
Helpful. My 17 yrs. old grandson had to take this course during his Senior, high school summer,. The book and workbook helped his get an A in this class, without an official teacher to assist him. He felt it was fun and adventurous to do on his own.