The students in Ms. Kahn’s class are talking about after-school jobs.

“I do some babysitting occasionally during the week, and almost every weekend,” says Kareema, “but I don’t know how I would cope with the responsibility of having a regular job every weekday. By the time I finish soccer practice, it’s almost dinner time, and then I’ve got to get my homework done before maybe watching a little TV and going to bed. Where is there time to work a regular job more than I already do?”

“I enjoy my job,” says Sergio. “I get my homework done right after school, then after dinner I go work for three hours at the movie theater. It’s fun to work with my coworkers and to talk with the customers about movies, even though I end up not having as much time as I used to for watching movies myself. Anyway, it’s great to acquire some spending money for the weekends.”

“Money is important,” says Viet Ly. “But I worry about how my older brother’s job affects him. He’s 17, and he works an eight-hour shift after school three days a week, plus another eight hours on Saturday. He’s saving most of his money for college, but ever since he turned 16 and started his job, he’s had a hard time sustaining good grades. He just seems rushed and tired all the time.”

Sergio nods. “Yeah, I think I’d have a hard time keeping up with my school responsibilities if I spent that much time on the job,” he says. “I guess it’s like Goldilocks and the Three Bears: I don’t want too much work or too little work. I like it just right.”

“But how much is just right?” says Viet Ly.

“Good question,” says Ms. Kahn. “Let’s see if we can find any research data on after-school jobs and academic performance.”

After doing an online search, Ms. Kahn’s students find the following graph summarizing the results of some research on the relationship between after-school employment and grade point averages for high school students.