Sentence 1: The professor explained today's experiment. 
 Sentence 3: I ignited the Bunsen burner to heat a substance 
 Sentence 4:  Since i didn't release that the gas was running, a flame sparked 
 Sentence 5:  It burned off a part of my eye-brow 
 Given Sentence 2: She leaned over the side of the bed  to look outside.