Glass absently explains the exercise underway while she peers at Amariah and Kas. And then she chews her lip a bit and says, [There's a weak attractor in Bells to find our - intended significant others - attached to useful resources; I think that's why Kas can read the alethiometer like it says in the Bellbook. It also plays to some template strengths - he didn't have to be as good at it as he is, but even if he weren't a true intuitive reader he'd still be good at it.]