One day, in an English class, the students are doing their lessons. Their teacher, a young woman, is very happy. She sings some nice songs with them and then she goes to the blackboard and writes "SMILES" on it. "This is the longest word in English, " she says to the class. A girl stands up and says, "It has only six letters. How can it be the longest word in English?" The teacher smiles and says, "Oh, look! There is a mile  between the first letter and the last one. " What does the teacher write on the blackboard?
Her name. A song. A word. A letter.