Parents who vary in their experience with formal schooling are likely to use different types of informal guidance with their children. However, rather than assuming a deficit approach we need evidence regarding how parents with limited schooling support their children's learning. Forty U.S. families of Mexican-heritage, from two levels of schooling experience, engaged with their children in a sink-or-float activity. Parents' questions and evaluations and children's decision-making and questions were observed and coded. Parents with higher schooling asked more questions and made more evaluative comments about their children's performance, whereas parents with basic schooling tended to evaluate their own performance more often. Parents made more decisions about items overall; however, children whose parents had basic schooling made more decisions and asked more conceptual questions than those with higher schooling parents. Children of higher schooling parents asked more procedural questions. These findings suggest that parents with basic schooling engaged with their children as collaborators, using open-ended inquiry. Conversely, parents with more schooling experience took an instructor-like role, which may have limited children's opportunities to engage in critical thinking.