Because these lessons are intended to teach you about using Standard American-Yellow Card, I won't say anything more about these other systems. I have at least four spades. If opener starts with 1 then responder has to have at least 10 points to bid hearts. Oddly enough responder will have to have five hearts to make this bid. The explanation will be given in just a moment.
Responder has an invitational responding hand or more Now responder has more lee-way in the bidding.
This means that she should bid her longest suit at the lowest level. Responder should bid her long suits as cheaply as possible. If two suits have the same length, then she should make a bid in the suit which is the lowest one above the opening bid. If opener has bid 1 and she holds K73 T3 KQJ5 Q732 then she should bid 2 . It's not the greatest response, but it's the most honest one.