Sentence 1: Sammy was going outside to check the mail. 
 Sentence 3: He had come outside through the open door 
 Sentence 4:  Sammy yelled for him to go inside 
 Sentence 5:  The toddler was upset, but he went in 
 Option 1: While he was checking, he noticed his two puppies outside. 
 Option 2: While he was checking, he noticed his toddler outside.