This quasi-experimental study aims to measure the effectiveness of using loose parts as a media to enhance problem-solving, critical thinking, and creativity skills among K2 students at Kindergarten XYZ Jakarta. The research involved a control group of 26 students and an experimental group of 25 students, using pretest and posttest assessments to measure progress. The experimental group integrated loose parts into classroom activities, while the control group followed the standard curriculum. Next, the pretest and posttest data are analyzed for their n-Gain values to obtain the difference between the two groups. N-Gain is used to measure the effectiveness of an intervention or learning approach by comparing score improvements between pretest and posttest, providing an overview of the extent of improvement in the use of loose parts in the experimental group. The higher the n-Gain value, the greater the improvement achieved by that group. The results showed an increased average score in problem-solving and creativity for the experimental group compared to the control group in both pretest and posttest. However, critical thinking scores showed no significant difference between the two groups. This suggests that the use of loose parts positively impacts problem-solving and creativity in kindergarten students, but improving critical thinking may require further investigation or alternative strategies.