In the statement that you will submit with your Change of Status application to USCIS, you will need to explain how and when you decided you wanted to do research/teach at Temple University. Since you did not intend to be an Exchange Visitor at the time of your visa application at a U.S. Embassy or Consulate abroad, describe very carefully how you came to change your mind. You should not have reached such a decision quickly; rather, the decision should be based on new information you received from reading, speaking to friends from home, or talking to other people.
The immigration officer who reads your application may suspect that you knew you were going to be an Exchange Visitor before you entered the US. If s/he suspects that you knew, s/he may consider your original application for your current visa status fraudulent and deny the application.
Since you changed your mind after arrival in the United States, you must be very clear about what influenced your decision. In your letter, you should explain your specific professional intentions. You should also address such questions as " Why is it better for you to conduct research/teach in the United States than in your home country?" and “What are your long-term plans?”
Please note that J-1 status has non-immigrant intent. This means that you will need to convince the USCIS officer that you intend to return to your home country. You should demonstrate how conducting research/teaching in the United States will make a better life for you in your home country. It is critical that you confirm that your intent is to eventually return to your home country. Keep in mind that the Exchange Visitor (J-1) status is a non-immigrant classification and that your plans must be to remain temporarily in the United States.