An is a digital document (usually downloadable and printable) designed for students in Secondary 2 (typically 8th Grade or ages 13-14). The "S2" level varies slightly by educational system (e.g., Hong Kong, Singapore, UK-based curricula), but universally, it represents a crucial bridge between basic literacy and advanced analytical reading.
A high-quality must address these four pillars. If a PDF only asks multiple-choice questions about facts, it is too easy for this level.