Until the pandemic, Jordyn and his mother, Precious Coleman, lived in Battle Creek, Mich., where he was known among his teachers as a bright but easily distracted student, capable of soaring when he was engaged.

On the day of a standardized test, Jordyn sat in front of his computer, humming to himself and spinning around in his chair. His teacher thought he was goofing off — until the results came in.

When his mother came to pick him up, a school administrator was waiting for her, and she worried Jordyn had gotten into trouble. “That’s when they told me that he had gotten not just the best score in his class but the best score in the entire grade,” she said.

After the pandemic hit, Ms. Coleman struggled to make ends meet. She and her two sons ended up moving to Clarksdale, Miss., one of the poorest corners of the United States. Ms. Coleman works an overnight shift at a casino. Jordyn waits for her to return home in the morning so he can log in to school with her cellphone, and she struggles to stay awake to help him.

Now Jordyn is at risk of becoming one of the lost students of the coronavirus pandemic in the most disrupted American school year since World War II.