"Kids who are working for pay in the U.S. and other countries underperform those who are not working for pay," Dr. David Post, associate professor of education at Penn State told CBS Radio News. "Boys, and to a lesser extent girls, show substantial negative effects on math and science achievement."
Post and Dr. Suet-ling Pong, associate professor of education, looked at the National Educational Longitudinal Study (NELS), a 1988 random sample of 8th graders across the U.S. that followed students through high school. NELS collected data on student's families, in school and after-school activities and tracked their academic progress.
"We could distinguish between light work (such as baby sitting and delivering newspapers) and heavy work (such as farm work or construction)," Post told the annual meeting of the American Sociological Association in Chicago Sunday. "For boys, clear evidence exists that working during 8th grade has detrimental effects on achievement and on learning math and science in the 10th grade. The evidence for girls is less dramatic, but still significant."
Post admitted that working after school may not be all bad.
"It could be that in some countries, including the U.S., the skills you learn on the jobs may be helpful in teaching you punctuality, respect for authority, being a model student," he said in an interview. "All these things help grades."
Previous studies, which looked only at grades, indicated that working had no effect. But the Penn State researchers looked at math and science achievement, not grades, and found a negative effect.
In fact, those male students in 8th grade who worked at farming, construction or commercial sector jobs more than two hours a week, were more adversely affected than those in traditional jobs like yard work or babysitting.
However, the students doing light work were also adversely affected as compared with those students who did not work at all.
"The reason I believe it has this effect is because it's competing with schoolwork for kids' time and energy," he told CBS.
Educators have argued that working while in school has benefits not obtainable through formal schooling. Hours spent working rather than doing school work increased students' sense of responsibility, interpersonal relationships and self image and allowed them to interact and learn from their elders. Now, the "adult" supervisor in charge is likely to be 18 years old.
Many jobs give kids little else than hourly wages as they operate fast-food cash registers having burger and soda coded keys rather than old-fashioned numerals and not requiring even the rudiment of arithmetic.