Young children naturally engage in mathematics as they play and explore. Although many early childhood educators are aware that children are frequently interacting with mathematical ideas, a certain level of knowledge and awareness is required to identify and highlight the mathematics that children are engaging in and to create opportunities for them to notice and explore mathematics. Because early childhood mathematics is far deeper and more complex than it may appear on the surface, the authors have immersed themselves in research on learning trajectories and developmental sequences of problem types and typical child-constructed solution strategies. Their professional learning equips them to notice and highlight important mathematics occurring in children's play as well as to plan purposeful opportunities for children to experience mathematics. Specifically, Cognitively Guided Instruction (CGI) has influenced the authors' instructional practices in the preschool classroom. Jessica F. Shumway conducts research on children's development of number sense at Utah State University. Lauren Pace is the lead preschool teacher at the Dolores Doré Eccles Center for Early Care and Education (DDE Center) at the university. Together, they have studied CGI and used this framework in Pace's classroom to watch their students' problem solving and reasoning develop. The purpose of this article is to share the ways that they have implemented word-problem tasks in the preschool classroom to promote problem solving and reasoning.