A caveat to this is that the person needs to be trainable. There are plenty of people that just can't absorb and process information, either at all or just quickly enough to not be an impediment to the rest of the team.
Also, if you don't know, and you said you did, make a great effort to know before you are needed to know.
Be sure to follow the rule before you head out.
Rule: You must post before you leave.