Plumber, electrician, tile setter, carpenter, roofer, glazier...
Please, do NOT go into social work thinking you can help children in the system. There are so many reasons why crappy foster parents get child after child.
As a social worker, you'll do your best to help them while they're within your workload (you will be overworked, and the kids will know it).
--Source: Foster child turned Masters of Social Work from a Michigan university, turned "Nothing I can do helps them, so I quit."