It's the personal a, it doesn't translate into English but you just use it when referring to a person or beloved pet.
Here's a really good explanation of it: http://spanish.about.com/cs/grammar/a/personal_a.htm
I think to say "I introduce myself," you'd say "me presento." I don't know the difference between "to the students" and "the students." I translated the sentence as "I present to the students." I'm pretty sure present and introduce are interchangeable... (I was thinking like give a presentation to the students).
I think it should be:
«Yo presento a los estudiantes» = "I introduce the students"
«Les presento a los estudiantes» = "I present to the students"
«Me presento a los estudiantes» = "I present (introduce) myself to the students"
If a native Spanish speaker happens to see this, could you clarify please?