Models of Evaluation

I have started Module 4 about Evaluation, and I am a little confused...the 3 models suggested are not clear to me.

Part of the problem I see here, is that I am planning a unit that includes online components, but is not totally online. So there are some distinctions that I need to make, and maybe the simplest is to focus the work of my project/unit of work on the components that will be solely online.

The naturalistic evaluation seems like it would be more difficult to method to utilise in the online environment, whereas it is one of the simplest when working face to face with students.

I will need to think hard about these models and my context that I am applying this course to.