How do you report hours that vary week to week?

I picked up part-time shifts as a welding apprentice and I am confused about how to report them. I worked as a welding apprentice before this. The form asks for gross earnings, which I do not see until later. Who can I ask without risking my claim?

In my state the question was about the week I worked, not the week I was paid. Read the wording on your form carefully, or ask the claims line.