On school days, employed high school students spent 42 fewer minutes, on average, on educational activities than their nonworking peers.
Employed high school students also spent 42 fewer minutes doing leisure and sports activities and slept for 36 fewer minutes than high school students who were not employed.
Employed students spent about two hours per school day, on average, on work and related activities.
These data are from the American Time Use Survey. You can find out more in Variations in time use at stages of the life cycle, Monthly Labor Review, September 2005. These data are for individuals, ages 15–19, who were enrolled in high school and on days they attended class. School days refers to days the students attended class.
Bureau of Labor Statistics, U.S. Department of Labor, The Economics Daily, Daily time use of high school students at https://www.bls.gov/opub/ted/2005/oct/wk4/art04.htm (visited August 19, 2022).