Sub: Permission for visiting XYZ factory .
I, XXX, am a student of class [ ], and a citizen of New Delhi.
We, the students of school [ ], have neem assigned a task of preparing a project on "the working/functioning of a factory". I am writing this letter to officially ask for your permission to visit the well accomplished XYZ factory on behalf of my co-students, for the same. As per your convenience and guidelines, we may visit your factory on a specified date. The factory premises will be visited responsibly by the students of our school, avoiding any kind of damage to your unit.
Requesting you to look into the this and permit us for an educational visit to your factory.
(phone no. )