The kids know. Don't think they really care.
At primary school my main points were
Can walk from home
Nurturing, building confidence etc. Academic stuff was secondary. I mean I wouldn't have wanted to send them to a school with real problems but round here they are all ok so fine.
I know they are clever because they always said so. I never brought it up. I was more interested in if they were happy, making friends etc.
DD1 especially. Same every year through primary. Now at secondary last parents evening was funny/ silly as each one we saw (bar PE and drama) said well she's very clever works really hard please can she do this GCSE 
BUT I'm like ok great but does she have many friends? Is she happy? She has always played things close to the chest. I wanted to talk to her form teacher but apparently that doesn't happen.
And that is what I want to know. Yes she's clever yes she works hard but is she happy? I KNOW she's shy. I know she avoids pairing with other children in eg CDT or whatever it's called now. And works on her own. The teacher put this down to focus and confidence. Said she's brilliant! The answers she gives to questions are 3 steps on in where I'm leading.
But. Is she happy? I'm not finding out.
In context. I was quite clever. I went to a clever school. There were girls there who had really major issues going on. No pastoral care. All that mattered was grades.
In the world of work TBH it's a mix of things that gets success, not just being academically good.
In short. Lots of kids are clever. Lots of kids work hard. In the end it's a combination of being able to get on with people, being able to persuade people, putting the work in when it's needed, and a desire to succeed, as well as having a reasonable but not necessarily massive amount of intellect, that gets you somewhere.
I mean unless you want to go and work at CERN or NASA or something but even there you need to be able to get on with people :D
(I wanted to work at CERN or NASA :D hence those examples!).