Parents can play a key role in their children's homework activities; this has been particularly true during the home-schooling caused by the pandemic. However, how parents affect students' mathematical activity is scarcely researched, in particular in the case of primary school students. Within the framework of activity theory, in this contribution two case studies are compared and contrasted to investigate how parents can influence the different aspects of their child's mathematical activity at home. Findings show that parents may play a role in many homework activities, including interpretation of the tasks. In particular, parents can influence the division of labor and the rules, in particular the normative aspects about the solution to be given that is the outcome of the homework activity.