My middle son wanted to go to the IL. Math and Science Academy, his junior and senior years. We started going to meetings about it when he was in the 6th grade. His HS was small and really not very good. We could have sent him to a Catholic school but it was pricey. IMSA was free, but 3 hours north of us.
When the time came, his dad couldn't stand to see him leave, so DS changed his mind. He studied on his own and sought out learning opportunities outside of HS. He served as a Congressional page.
When he went to the U of Chicago, he found out what a really poor HS education he got in central IL. He was taking classes that the WIlmette kids had had in HS. So, he had to play catch up.
Some HSs just aren't very good. (But they were number 1 in baseball.)
