How to warm glass jars of store-bought gravy before taking to school?

[Anonymous]

Anonymous wrote:We're specifically asked to bring the jars, not gravy put in something else.

I would still have him bring it in a thermos. Send a jar in and warm it with warm water on the outside and transfer the gravy into the jar.

[Anonymous]

warm water bath in a crock pot?

[Anonymous]

As the OP, I'd like to thank you all for your advice. You have been so generous with your time.