Download and read the article, "The Impact of Children's Work on Schooling: Multi-Country Evidence based on SIMPOC Data by Ranjan Ray and Geoffrey Lancaster. You can find this article on the website http://repec.org/ esAUSM04/up.15362.1076562558.pdf.

To understand the effect of child labor on school participation, why is a measure of child labor in terms of hours worked per week more satisfactory than a measure of child labor participation (whether a child works or not)? What does the article conclude about the effect of child labor hours on school participation? The authors find that the results in Sri Lanka are different. Do some research to find an explanation for the Sri Lankan experience.