This study followed a process-based approach, in which variability describe the changes that occurs moment-to-moment. The aim of this study is to explore the intra-individual trajectories of the joint use of the numerical cardinal and the notation of quantities. Twenty-three preschool children of 4-5 years old participated on the study. The children were attending public school in Cali-Colombia. Regarding the method, a microgenetic design and a task called “Give and Note a Number” was used to capture the variability of the children’s performance. The task was an adaptation of the task “Give a Number” by LeCorre and Carey (2007). The technique of cluster analysis was implemented for data analysis. The results revealed some patterns of the intra-individual trajectories of the children’s performance: (1) five patterns of cardinality, (2) five patterns of notations, and (3) several joint profiles to“give” and “note” quantities. In conclusion, our findings suggest a dynamic process of the joint use of the cardinality and notations,showing the co-existence of different levels of complexity.