Stacked Up employs data journalism to explore the hidden book crisis in Philadelphia schools. Most people would be surprised at the idea that a public school wouldn't have enough books. In Philadelphia, however, students and parents regularly complain of textbook shortages. A 10th grader at Parkway West High School told me that students often have to share books in class and can't take them home to do homework. Many books are in poor condition: "There were pictures of testicles drawn on every page," she said of one of her ninth-grade books. Access to books is particularly critical because a school today is labeled a success or failure based on students' performance on high-stakes tests. The tests are highly specific and are aligned with state educational standards. The tests are also aligned with the textbooks sold by the 4 educational publishers that dominate the educational publishing market—the same publishers who have a hand in designing and grading the standardized tests. It therefore stands to reason that if students don't have the right textbooks, they won't be able to do well on the tests even if they want to.