As an instructor, the Pygmalion effect will be great if you use it in a positive way. Telling the class today's lecture will be interesting, the exercises will be fun, achieving a higher wpm in typing gives them better opportunities when they start looking for a job, etc. When I group students, I make sure that there is always a student who would be positive enough to help the other students in the group. Giving positive comments encourages students to have a positive outlook regarding that module. They arrive to class excited with what that day will bring. What new ideas they will learn, what new skills they can apply that will get them ready to work. All these helps motivate for the students to come to class.