Is there a way you could arrange a short play date with a current student? Maybe the teacher can help with a compatable suggestion. I would suggest somewhere that is a easy situation like your home if sharing is not hard or somewhere that he feels comfortable like the library.
A book called, "The kissing hand" helped my kids with learn how to miss a Mom. Sometimes giving a child something of yours to have with them can help.
HOw about a picture of you on a keyring attached to his school bag to look at during school. If he is missing you at school can he make a picture and tell you about his feelings.
I use to make a paper heart for my son for many months during preschool and then I'd kiss it and leave a lip stick mark. Eventually, he told me he did not need it anymore.
I hope it is better next time. good luck. Let us know how it goes.
