While circuitry lessons have traditionally been first introduced in late elementary school, they remain challenging conceptually for undergraduates in physics and engineering courses. Seeking to provide a higher quality and earlier introduction to circuitry learning for young children (ages 3-5), this paper investigates the affordances of utilizing the Squishy Circuits toolkit, a circuitry kit that combines circuit components and playdough, as a first introduction. Our study engaged 45 children across three nursery school classrooms in open-ended play with Squishy Circuits toolkits for seven sessions over a period of 2 weeks. Here, we focus on six children in one focal classroom in order to illustrate the concepts that children are developing during play and open exploration with the kits and a range of crafting materials. Findings indicated that the Squishy Circuits toolkit enabled children to explore concepts important to circuitry learning, including current flow, polarity, and connections. Additionally, analysis of whole class conversations before and after the circuitry explorations indicated significant gains in children's ability to discuss circuitry concepts over the course of the study. Through individual case studies, we illustrate how children enacted these concepts through their play and how the transparency afforded by the toolkit make the big ideas of circuitry visible. This work serves to illustrate how very young children can successfully begin to engage with science topics commonly introduced in later elementary school when those topics are framed through play and discovery with transparent and malleable materials.