Who is answering the question (SPEAKENG) about the English level for children (between 5 to 16)? Are the parents? are children reporting their level of english?
Assuming you are referring to the ACS data, generally the questionnaire is completed by a single individual for everyone in their household. The Census Bureau is not explicit about which household member should complete the questionnaire, but it seems reasonable to assume that children wouldn’t usually be completing it. You can find past questionnaire and instructions here: Sample ACS & PRCS Forms and Instructions
Each decennial census used its own procedure for interviewing households. IPUMS has compiled the questionnaire forms and enumerator instructions for each census here.
Thank you Matthew, I forgot to mention I am referring to the historical census, 1860 to 1900
In the historical censuses, it will almost always be whoever talked to the census taker answering for everyone in the household. This was frequently the head or their spouse. Every once in a while, diligent census takers might go back to a certain household when they were unable to complete the census on their first pass, and in that case might have talked to a different member of the household, but this was reportedly quite rare.
The 1900 census was the first that specifically asked about English speaking ability; this information was only ascertained for those age 10+ (see the universe tab for SPEAKENG). In previous censuses, literacy (LIT) recorded whether the person was able to read and/or write in any language.
While documentation for the 1900 census does not provide instructions for who in the household could provide responses for other members, common established practices for interviewing are outlined in the instructions for enumerators in the 1880 census:
It is by law made the duty of each enumerator, after being duly qualified as above, to visit personally each dwelling in his subdivision, and each family therein, and each individual living out of a family in any place of abode, and by inquiry made to the head of such family, or of the member hereof deemed most credible and worthy of trust, or of such individual living out of a family, to obtain each and every item of information and all the particulars required by the act of March 3, 1879, as amended by act of April 20, 1880.
That each and every person more than 20 years of age, belonging to any family residing in any enumeration district, and in case of the absence of the heads and other members of any such family, then any agent of such family, shall be, and each of them hereby is, required, if thereto requested by the superintendent, supervisor, or enumerator, to render a true account, to the best of his or her knowledge, of every person belonging to such family in the various particulars required by law, and whoever shall willfully fail or refuse shall be guilty of a misdemeanor, and upon conviction thereof shall forfeit and pay a sum not exceeding one hundred dollars.
While the default appears to have been to collect information from the head of the household, it could also be collected from the household member “deemed most credible” or from any person over the age of 20. The instructions consistently reference a single household respondent, rather than the entire household being interviewed. Therefore, information on English speaking ability would likely be collected directly from the household respondent for all household members.
An additional note in the instructions states that “the enumerator is not required to accept answers which he knows, or has reason to believe, are false.” It’s possible to imagine a case where a household respondent reports that a child can speak English, but from observation that the enumerator determines that they cannot and will indicate this instead. However, I’m not aware of any documentation that reports how often this would have happened.