Probability

I'm trying to teach myself probability, but it's really difficult for me to understand.

I'm trying this question from a textbook I've downloaded online, and I just can't seem to wrap my head around it.

Question 1. a) There is a family of 3 children. You saw one of the children, and it's a girl. What's the probability that all of them are girls?

1. b) You saw another child. You're not sure if it's the same girl you saw. What's the probability that all of the children are girls? Is it the same as question 1. a)?

Ok, are you leaving something out of problem b?  Because the way I read it is like this:  You see one girl in the family of three.  Then you see some other child.  No information is given about whether or not that child is in the family or about gender.  Unless we're calling the observer effect, I'm not sure how it's even relevant that you just saw some child.