Perhaps you may measure this indirectly through social position of children's parents.
You may assess their SES instead. Usually you ask about annual income or education qualifications. For children it could be school ranking or area they live.
you might also Check the family affluence scale, which has been used in the HBSC study on adolescents aged 11 to 15 years for several years now. This scale is a validated measure consisting of different household items.
Best, timo
Ps.: You might also check a publication from me where we (more or less) compare different SES measures in adolescence:
Lit.: Pförtner et al. The use of parental occupation in adolescent health surveys. An application of ISCO-based measures of occupational status. Journal of Epidemiology & Community Health 2015; 69:177-184