A growing body of research concerned with computational thinking (CT) has emerged the last couple of years, but there is still a lack of consensus about the definition of CT. There are also gaps in the understanding of how young children manifest CT. With this paper, we contribute to the field by taking an action perspective with the CT of K-3 students. The analysis focus on iterative acts of abstraction and decomposition as a core process that elicits development of CT. We call these iterative acts the Abstraction/Decomposition spiral (AD spiral). By illustrating the AD spiral through the actions of two first grade students, the analysis shows how visual representation of an emerging solution, and the development of a plan are two important elements when young students solve problems in a coding context, developing their CT.