Presenting differences in the participation rates of genders in STEM activities may be a practical way to reveal that a solution to the gender gap should include addressing children at an early age, rather than at later periods in life. Thus, the purpose of the study was to investigate the STEM-related activity preferences of 3 to 8-year-old children. The sample of the study consisted of 193 children, between 3- and 8-years old attended STEM activities presented at the eight-hours-long science fair annually organized. Data was collected through a checklist. The results of the study revealed that the number of boys that attended the activities was greater than that of girls. More boys participated in the age group 5 than girls. On the other hand, girls' participation was higher than boys in age group 6. The results of the study also revealed that the activity preference of girls and boys did not differ for five out of six activities, i.e., Catapult Design, Jumping Wooden Sticks, Design Own Ship, Rescue the Horse, and Constructing with Mirror. However, it was found that among the six activities, boys participated in the magnetic wall activity significantly more than girls. This study may indicate the basis from which the gender gap emerged in STEM-related fields.