Modern children are taught grammar, with concepts such as fronted adverbials and the like. My children were taught parts of speech, clauses and sentence structure 25-30 years ago, and I had lessons in parsing sentences in the 70s.
My own contributions on this thread are about rejecting the idea that younger people are somehow 'inferior' (for want of a better term) to older ones when it comes to English Language, as in my experience there are plenty of examples of older people whose grasp of relatively basic English is lacking. It's not a generation thing, or an intelligence thing*, it comes down to education, and modern children are in education for far longer than many older ones were. I think it is a mistake to assume that young people's English is not as good as that of older generations.
*As far back as the 60s, Labov (a sociolinguist) studied speech patterns of children in disadvantaged areas (specifically Harlem and areas with high concentrations of Puerto Rican Americans), and found that their speech patterns, whilst noticeably different from 'Standard American' were equally rules-bound and complex - not 'inferior' at all. Subsequent studies have reinforced his findings with different social groups. Standard speech patterns are perceived as having higher status, but that is arbitrary and nothing to do with being intrinsically 'better' or more complex than other ones.