Hello

Could you tell me please if the sentences below are correct?
1.
Work with teenagers can be hard.
2.
The work at your school would constitute a great source of experience for me. (I have already mentioned the post I would like to apply for).
3.
The work with students was very challenging. (I have already explained what kind of work it was)
4. I adore working with students of various age and at all levels of advancement. What I adore the most is
the/- work with primary school pupils.
(I think no article should be placed here...)
Thank you for your help!
I would really appreciate it.
Kind regards!