All's quiet on the kindy front

I do part time work at a language center for classes of 6-8 year olds. This kindergarten class has 20 something 6 year olds and their Korean teacher often "wanders" out of class leaving me to face them ... Keeping them quiet with cut outs of the letter H and having them glue the letters to corresponding animals kept them content for about 10 of the 30 minutes in class. I made the mistake of teaching them "help me" so now when they finish 20 children repeatedly scream help me as if I didn't hear the first time.