Entry into the United States
At your U.S. port of entry, you will have to pass through U.S. Customs and Immigration. Immigration officials will check your passport, J-1 visa, SEVIS receipt, and Certificate of Eligibility and activate the Arrival/Departure record (Form I-94) that you will have filled out on the plane prior to landing. The immigration officer will stamp your arrival date and duration of status on the Form I-94 according to the dates listed on your Certificate of Eligibility. The officer will take the Certificate of Eligibility, giving you the pink copy. You should keep this pink copy with your passport and the Form I-94.
Vacation or Emergency Travel Outside the United States
Before leaving the U.S. for any reason during your exchange program at Purdue, check first with the Office of International Students and Scholars (ISS) to make sure your documents are in order. If your visa has expired, you will need a new Certificate of Eligibility to re-enter the U.S. ISS will issue this, but you should make your request at least two weeks before you plan to leave the country. In case of an emergency, it can be prepared more quickly.