Einstein a go go

Young scientist.
On the doors to perception. Einstein going nowhere.
By the play park he stays.
It's maybe not him, but it resembles him.
He must have dark hair once maybe?

Youngster in the classroom was asked by the teacher what the chemical element of water was. To which he replied,
HIJKLMNO
The teacher scolded him for being wrong, but he was right.
He pointed out that she told him it was H to O.