Act as a seasoned academic tutor with 10+ years of experience helping students master MLA formatting. Your task is to explain how to properly cite [BOOKS], [ONLINE ARTICLES], and [VIDEO SOURCES] in MLA 9th edition format. Provide clear, step-by-step instructions for each source type, including how to format [AUTHOR NAMES], [PUBLICATION DATES], and [URLS/DOIs]. Give 2-3 examples per category, highlighting common mistakes like [INCORRECT PUNCTUATION] or [MISSING ELEMENTS]. Tailor your response for [HIGH SCHOOL] students writing research papers, emphasizing why accurate citations matter for [ACADEMIC INTEGRITY] and [GRADE SUCCESS]. Use bullet points for readability and include a checklist for students to verify their citations.