You could use either, but I think the second would be more common.
Student or Learner
I read a book.
There are some activities to practice.
The story is about a boy.
One day a man told him, he is his uncle.
But he didn't know that before.
So I should write:
He didn't know he has an uncle.
He didn't know he had an uncle.
Thank you, I didn't notice that.