I think I understand this well. It reminds me of the exercise where students have to explain to someone how to make a PB&J sandwich, but they run into trouble because their instructions have to be more detailed than they expect (such as remembering to tell the person to unscrew the lid to the peanut butter before telling them to spread peanut butter onto one half of the bread).

This concept is still a little confusing to me. I want to understand it better than I do now. Are they saying that there is the possibility of using assumptions to extrapolate or create data that does not actually exist in a measurable, specific, and observable way?

And it allows for the data to be reviewed and observed later by other researchers!

Interesting and amusing. I like that the author describes it as an "easy" reaction.

I think it an essential tool for observers to be able to identify what in their observations is data and what is supposition. Notes on a person's behavior for example: "The student quickly became totally bored and disengaged the when the teacher was lecturing about muskrats and couldn't wait to go outside to play" is supposition whereas "Approximately 2 minutes into the teacher's lecture about muskrats, the student stopped looking at the teacher and instead began tapping their pencil on the desk and looking out the window and did not stop this behavior until the lecture concluded and the students went outside for recess." is data.

I'm not sure I totally understand this. Is this them comparing and contrasting previously selected activities?

I think this is so important, but very difficult. In circumstances where there is little data or prior ethnographic study, the observer may not be able to obtain this understanding as they are the pioneers in the study. That being said, I think that many first observations must be looked at with a different lens.