Homework is a key element of secondary schooling across many contemporary education systems worldwide. However, debate about the value and efficacy of homework at the secondary school level is ongoing. Proponents of homework promote its numerous benefits for learning and achievement, while critics challenge the merit of homework, and highlight the potentially detrimental impacts it can have on student learning. Overall, the evidence from current research and literature shows that homework at the secondary school level generally has a positive impact on student academic achievement and learning. However, many factors and variables can influence this link in both a positive and negative fashion. These variables include: parental income and socio-economic status, parental support vs. control, quantity of homework completed, and overall time spent on completing homework. The research also suggests that homework is most useful and effective when it is used to expand upon concepts already taught in class, and when students have intrinsic motivation to engage with and complete homework.