In chapter 4, we're using
Session.get('selectedHouse')
to get the current house selected, but in chapter 5 it changes to
Session.get('selectedHouseId')


Just wanted to point that out, it's not a huge problem

Also, you could probably talk about the use of this alternate syntax to get a value inside a template event map:

tmpl.find('input[id=username]').value; // tmpl is the 2nd argument of the function) 


instead of:

$("input[id=username]").val();