I equate attendance with participation. I assume that if the student is showing up, s/he is getting something, even if not verbally participating.
As for the return of the first assignment, yes, it is a bit like the honeymoon is over. I have instituted a "drop" technique, where I drop the lowest mark of the first four or five assignments, unless the low mark is a result of plagiarism or cheating. My assignments, then, add up to 105%-115%, from which I drop one mark.
This technique gives me a chance to be "harder" in my initial marking than I may want to be, but I don't want to give false impressions to students either. Students are far more accepting of their first F when they know it won't be counted, and they seem more willing to learn from it. Students also may be more willing to take risks if not everything counts against them.
This is manageable in the smaller classes I teach. The logistics would be crazy in larger classes.
Judy Johnson