Maybe you could be a good writer—maybe even good enough to write a book or articles in a newspaper—but you might not know it until you write a paper for your English class. Maybe you could be an innovator or an inventor—maybe even good enough to come up with the next iPhone or a new medicine or vaccine—but you might not know it until you do a project for your science class.
In this section of the speech, the purpose of the parallel structure is to help Obama
1: emphasize his belief in the importance of being able to write well.
2: explain his thoughts on the best classes to take for a good education.
3: prove his point by spelling out the options available with an education.
4: strengthen his argument that more scientists are needed in the workforce