Sentence 1: The teacher was going over a new section in class. 
 Sentence 3: When she opened them, the whole class was staring at her 
 Sentence 4:  The teacher paused for a moment, but he eventually continued 
 Sentence 5:  Diana went to the bathroom to freshen up 
 Option 1: Diana couldn't keep her eyes open and fell asleep. 
 Option 2: Diana couldn't keep her eyes open and fell asleep, but no one noticed.