There are several elements teachers can use to build their lessons including (but not limited to) modeling, discussions, research and explorations, assessments, and collaboration. Catlin Tucker talks about these activities and discussions how to building online and offline activities for learners in her blog post The Building Blocks of an Online Lesson

The tools teachers use to engage students online are indeed different. It is also true that engaging students in learning activities online will require (at least initially) that teachers onboard students to those technology tools and support them in learning how to navigate online tasks. However, the activities and tasks teachers use to create their lessons offline can be transferred to the online environment if teachers know what tools to use.

Source: The Building Blocks of an Online Lesson