Final answer:
The first task when beginning a new lesson is to read the section in the textbook, with accessibility referring to the course content's usability, and valid sources for research being credible and official materials.
Step-by-step explanation:
When you begin a new lesson, your first task should be to read the section in the online textbook. This foundational step allows you to comprehend the material before filling out any knowledge charts, taking assessments, or organizing notes. As for accessibility, it refers to the usability of course content regardless of a person's ability or disability, ensuring that all students can engage with the material. Valid sources for online research typically include academic journals, scholarly databases, and official websites; you should always aim to locate those other sources to ensure the credibility of the information you present in any academic work.