Thing 23, which concerned affective outcomes, had me thinking about how to assess them. One useful point was that the assessment need not be formal. Basic observation can help us adjust our lessons to how learners are feeling or to where learners seem stuck. After completing Thing 23 I was teaching a lesson. I noticed how a handout was confusing for the learners, who were novices. Afterward I revamped the handout to better serve the next class. For those teaching online classes think of the introduction posts: Those are an excellent place to get a feel for where learners are emotionally.
The other useful point was that, as elusive as these outcomes are, they matter. If we are not in a good frame of mind to learn, the content will not stick. Besides, we are human, with human emotions.
For further reading I recommend
Cahoy, E. S., & Schroeder, R. (2012). Embedding affective learning outcomes in library instruction. Communications in Information Literacy, 6(1), 73-90.
This article was the source reading for Thing 23.