MINFORD, Ohio — Inside an elementary school classroom decorated with colorful floor mats, art supplies and building blocks, a little boy named Riley talked quietly with a teacher about how he had watched his mother take “knockout pills” and had seen his father shoot up “a thousand times.”

Riley, who is 9 years old, described how he had often been left alone to care for his baby brother while his parents were somewhere else getting high. Beginning when he was about 5, he would heat up meals of fries, chicken nuggets and spaghetti rings in the microwave for himself and his brother, he said. “That was all I knew how to make,” Riley said.

Riley — who is in foster care and who officials asked not be fully identified because of his age — is among hundreds of students enrolled in the local school district who have witnessed drug use at home. Like many of his classmates at Minford Elementary School , Riley struggles with behavioral and psychological problems that make it difficult to focus, school officials said, let alone absorb lessons.

“If you’re worried about your parents getting arrested last night, you can’t retain information,” said Kendra Rase Cram, a teacher at Minford Elementary who was hired this past academic year to teach students how to cope with trauma. Over the past nine months, she led several classes a day, and met every week in one-on-one sessions with up to 20 students who have experienced significant trauma.