Sentence 1: Kate's friend Sue sat at a desk behind her. 
 Sentence 3: They giggled and whispered and tried to be quiet 
 Sentence 4:  But their teacher caught them and gave them dirty looks 
 Sentence 5:  Kate turned around in a huff and finished her assignment 
 Option 1: When her teacher wasn't looking they turned to each other to talk. 
 Option 2: They didn't talk in class because the teacher was watching them.