I got this idea from an instructor I flew with when I was still a private pilot, and I did the same thing when I was a CFI.
After the lesson, I wrote down everything that we did in my logbook first. If it was the first time I flew with that student, then somewhere on the line I would write his/her first and last name; on subsequent flights, I'd write the first initial/last name. I would then insist that the students sign the line next to their name in my logbook. Then, and only then, would I put the exact same entry in their logbook.
This protected the student, by making sure everything was logged, and by making sure I couldn't later claim s/he did something I didn't teach if he or she crashed. It protected me by making sure that my log was always kept up to date, and also giving me protection from false claims by the student.
At job interviews later, my record-keeping impressed the hell out of recruiters and interviewers. It did the same when I took checkrides with the FAA and they were looking through my log for experience.
Just food for thought...