Conversation so far:
What position did Jahlil Okafor play as a junior in high school?
Jahlil Okafor played center in high school.
Which high school did Jahlil Okafor attend?
Jahlil Okafor attended Whitney M. Young Magnet High School.

Question: Which years did he attend?
Self-contained rewrite: Which years did Jahlil Okafor attend Whitney M. Young Magnet High School?