DS 160 Employment

[student_01]

I filling out my DS-160. I am completing my MS and I have an assistantship that will end when I graduate. I am starting my PhD after this, and I will be receiving the assistantship for the PhD as well. My question is:

 

As the assistantship for the MS will end when I graduate, should I list it as past employment? If I do that, should I just enter student for present employment/work? I'm a little bit confused, and I would greatly appreciate any assistance here. Also, should volunteer experience on OPT be listed under the past employment?

 

Thank you in advance!