One of the major differences between a Learning Management System (LMS) and face to face teaching is the course module. While teachers often think in terms of units and lessons, a module is different.
Lesson plans are plans for the teacher—what students are supposed to learn, how teachers will instruct students (the hook, the direct instruction, the check for understanding, the guided and independent practice, the wrap-up), and how students will be assessed. Lesson plans are typically parts of units of instruction, which have overarching themes and goals—human body systems, modern poetry, or statistics models, for example. Typically, units of instruction cover at least one and often several weeks of instruction.
This is fine, but this kind of organization does not translate directly to online teaching. Instead, the basic element in an online course is a module. If your course is a file cabinet, the module is the individual file folder. The Big 3 LMSs help teachers organize their course in modules. The number of modules depends on the length of the course.
In my experience, the module is best organized on a weekly basis. Our world organizes things by weeks, so all but the youngest K-12 students have an idea of how long a week is. Students and parents can plan by the week. Weeks do not automatically correspond to lessons or units, so teachers must change the way they approach planning.
Modules contain all of the course content for students. Files, notes, discussions, videos, class recordings, assignments, tests, quizzes, links—all of those components are organized within a module. Just like a file folder, modules are labeled for students.
Google Classroom topics are not equivalent to modules because the organizational flow is that of a social media feed, rather than a file folder. Finding a particular piece of information on a social media site is hard because they are designed to show new material. Old material needs to be readily available for students, which makes Google Classroom a bad choice for online classrooms.