This research aims to determine or prove that through block play activities, the cognitive abilities
of children in the first year grade of TK Pertiwi Clekatakan, can be improved. This Classroom
Action Research (CAR) consisted of two cycles, with each cycle comprising two meetings.
Problem-solving consists of four stages: Planning Implementation, Observation, and Reflection.
Data were obtained through observation, interviews, and direct documentation studies on the
research subjects, which are the children in the first year grade of TK Pertiwi Clekatakan, totaling
15 children, comprising 7 boys and 8 girls. Furthermore, the research data were analyzed step by
step using descriptive, qualitative, and percentage analysis from the initial study, Cycle I, and
Cycle II. After analysis, the research results show an improvement in children's cognitive
development. Initially, out of 15 children, there was one child (7%) with undeveloped cognitive
abilities (BB), five children (33%) were starting to develop (MB), four children were developing
as expected (BSH), and five children were developing very well (BSB). After Cycle 1, there was no
significant change in the distribution of cognitive abilities. Then, in Cycle II, there was an
improvement, with four children (27%) showing MB cognitive abilities, five children (33%)
developing as expected, and six children (40%) developing very well. In conclusion, there was an
overall increase in children's cognitive development from the initial study in Cycle One and Cycle
Two, totaling 73% of children, comprising 33% developing as expected and 40% developing very
well. Therefore, the research results indicate a success rate of 73% in Cycle II, exceeding the 60%
completeness threshold. In other words, the research was successful.