This has been developed to prepare students for standardized testing over the Common Core Standards in English (grammar and writing) for fifth grade specifically. The passage comes from released items from California Standards Test (2008) and a website on kids health. There are 15 questions related to grammar and editing. There are an additional 3 questions comparing the two articles, one short response, and one essay prompt.
You are not paying for the passages, but rather the time and effort it took to create questions, label them with standards, and compile and edit the document for student use.