Children's age vs school year 3, or year 7

[thatdamnmotherinlaw]

Why can't people just put their children's age in the post, instead of their school year 3, or year 7

Because it might be relevant if it

... is a post about school etc?

11 year old at secondary is contextyally quite different from 11 year old in primary in relation to things like homework, walking to school alone etc

Usually it is a post about socialising and friendships

Not every part of the UK uses the same school system so i don't know what age a year 3 or year 7 child would be.

I think this why I find this is frustrating