As was mentioned by Geomo, it is a good idea to print out your test results and approvals. I know you can have all this info on your smart phone, which I did, but it is much easier for the agents to see what they need to see on printed documents. The agents that we presented the printed copies had an easier time than the agents trying to read what they are looking for on your phone. This is what I witnessed on our trip. I followed this advise that was posted on this site and it will make your trip easier.