There are two E strings on the guitar: the top string and the bottom string. We are working with the bottom E string, which is higher sounding and thinner than the top E string. If you need help identifying the E string, you can check online to confirm. This exercise is designed to get the student used to moving between strings. It is very beneficial to be able to move between strings without having to look at your right hand.
As the student practices the given pattern and the patterns they create, have them work on not looking at the guitar. If the right hand thumb is anchored, they will eventually learn to feel which string they are on. One suggestion to give them to keep from looking at the guitar is to maintain eye contact with someone while they play.
Students start by playing the pattern G, B, E, B. Then they create their own four note pattern. The pattern itself is not that important, just that they are deciding an order to pluck the strings and sticking to it.