My school gives anecdotal reports instead of letter grades. What that means for me is a huge amount of observation, assessment, and writing. Lots and lots of writing.
With my first and second grade students this is laborious, but fairly straightforward- I consider their participation, behavior, feedback during class, and finished work to write my reports.
Thankfully, my older students can help me write more nuanced, detailed reports by filling out these self-evaluation forms. The self-evaluations give me a lot of insight into how my students feel they are doing, and they are almost always spot-on.
I pass these out twice a year, about two weeks before I begin my report writing process and write a list of projects and lessons we’ve done on the board to clear any hazy memories. I highly recommend you try something similar with your students- it gives them a voice in the assessment process!