What's the best way to measure socioeconomic status in kids?

Polling consumption habits will give a lot of false positives. Many people with a flashy lifestyle have a lot of debt. If consumption is not status.
Good questions to ask would be;
How stressed are your parents over bills?
Do your parents have to work 2 jobs or a lot of overtime to make ends meet?
Do you feel like you will afford to get an education?
What is your prime motive for working?
Do you have a savings account?
Does your family subscribe to any newspapers?