When you assign a student homework or some other thing that you expect them to complete either at home or at school, you need to hold them accountable if they do not turn it in. I used to have my students complete a Zero Sheet if they didn't have their assignment. On the Zero Sheet, the student had to fill in their name, the date, the name of the assignment, and the reason that they did not do the assignment.
Filling out a Zero Sheet did not mean that the student was no longer responsible for the assignment. I still expected them to do it, although now it was counted late. But now I had documentation in the student's own words as to what assignment they did not do and the reason they did not do it. This was invaluable information during a parent-teacher conference and often gave parents insight they needed. Parents were always amazed and often frustrated when they read the different excuses their child wrote.
Sometimes, I would mail the Zero Sheet home with a copy of the assignment and explain that the student could still complete this assignment.