There will be tears today. And grins. Delight over seeing old friends. And trepidation over making new ones. Teachers will charm children and worry them. Principals will be charmed — and will worry. This is the way it goes on the first day of school. So it is, so it seemingly has always been. Jeff Roth, the master of The Times’ photo archives, and Amisha Padnani, a Times Web producer who has covered city schools, assembled photos from the first day of school through the decades. Enjoy the slide show. And have a great first day.