Sentence 1: Alex was walking to school and saw a snail crossing the sidewalk. 
 Sentence 3: Then she saw three smaller snails following the first one 
 Sentence 4:  Alex watched and waited for all the snails to cross the sidewalk 
 Sentence 5:  She felt happy knowing that the snail family made it safely across 
 Given Sentence 2: She stopped to watch the snail.