כי סתם נשים בעולם אינם עשירות ועליהן מוטל גידול הילדים והילדות
translation from link
the average woman is not wealthy and has responsibility to raise sons and daughters.
but
ד אבל אמו אין מצווה עליו כלל בין במצות עשה בין בלא תעשה
my translation
But the mother is not commanded (to educate her son) at all not positive commandment and not negative
1) what (specifically) is the responsibility to raise sons and daughters (how is it fulfilled by the letter of the law? and above the letter of the law)? (since from shulchan aruch harav above it seems that it is not chinuch)
2) what are earlier (original) sources that they have this responsibility?