Susan H. Sachs
Since my family name was also originally Herskowitz / Herschkovics etc. - I follow the reasoning of many of the respondents.
Also, the suggestion to look at other census records, such as 1940.
Or these children may have been foster children, nieces/nephews of an over-burdened relative, etc. who were taken in temporarily.
Finally, unfortunately, 90 years ago there was still a much higher mortality rate for young children than today, especially since penicillin was not available then. So, sadly, you might want to check death records as well.
Susan Hersh Sachs
HERSKOVICS - Munkacs; KLEIN - Barkaso; WEISS - Gulacs
, Klein, Weiss - McKeesport