I think each child's development is very different. I have 2 kids, my girl is super smart and has extremely good memory. My boy is nearly 1 year old, at his age, my girl already knew some simple words but my boy refused to learn and doesn't know anything except saying nonono and says bye bye.
Some kids they don't need to be taught they are still bright (like my girl), but some kids even if you push hard they still know nothing (like my boy, I read him flash cards, he ignored, just grabbed the card from my hand and put in his mouth).
I never give pressure to my kids, just let them do what they want. as long as they are not the worst batch I feel happy. Even if you are bright now doesn't mean you can be a successful person when you grow up.
like me, I am as dumb as my boy but I have a better life than my husband who is smart but works like a horse under big pressure. I can be a full-time mummy enjoying my life
apart from knowledge, we must have to teach them ethics and control their emotions. i think this is a very important part. they should understand what is right and wrong. I'd rather my kids not as smart, than hitting, pushing, scratching people at school without a reason.