the most direct way for jonathan to gain on-the-job experience and earn money while attending school is to apply for:

This can be achieved by applying for the work-study program

Explanation:

The work study program : this allows the student in this case Jonathan to gain the required on-the-job experience and also earn some money while getting educated as well.

There are several ways of gaining on the job experience but you might not earn money while you gain the experience like taking up and internship program from an organization or company will give you the experience and might well allow you earn but it might ultimately not allow you attend school while on internship.

also the study program allows you study but you cant work while you study hence you cant get on-the job experience.

a work-study program, this is on the job experience