Help me think of an idiom to describe it: young people are self-motivated but have little knowledge, while old people are well-informed but unable to do so.

I think of a poem that fits this question very well.

Ugly slave

Shuboshan road middle wall

Song Xin qi Ji

Teenagers don't know the taste of sadness,

Fall in love with the floor

Fall in love with the floor,

Worried about adding new words.

Now I know what it's like to be sad,

I want to talk about it.

If you want to talk,

But it is a cool autumn.