A mentioned that he wished his school would add rock-climbing as PE elective. I told him that now was a good time to ask the school's administration for this because he had leverage. What leverage? He is in the process of deciding which high school to attend. His school is k-12 and encourages all students to stay there for high school. They know he is considering other high schools and will make an effort to retain him. I don't know if they will go as far as adding rock-climbing to the school's program, but now is certainly the best time to try.
I mentioned to the boys that when I am trying to hire people I sometimes get pretty extreme requests: "I am almost ready to accept this position but I have an issue. I booked a month long trip to Antartica next Winter". If this person was already working at my company and was full of responsibilities I might have a hard time agreeing to him taking a month off to go to Antartica. But when I am trying to hire him, he has a lot more leverage. If that is what it will take to get him, I'll probably accept. Besides, the person doesn't yet have responsibilities - and I can even rationalize that if I don't hire him, it might take me another month to hire someone else, so I wouldn't be any better off saying no.
It is similar to when you are negotiating to buy something: before you've paid (or agreed to pay) you might get a few extras from the seller (how about a set of mats for that new car?). After you paid? You are at the seller's mercy...
One final point: A hasn't yet heard back from the other high schools that he applied to. He might not get into any of them (other than his current one). But then he might. He shouldn't wait until he gets the answers because he risks losing his leverage if he doesn't get in. Moments of leverage can be ephemeral: take them when you have them!