Author(s): Nanneh ChehrasThe present study deals a novel science, technology, engineering, and mathematics gender gap measure to document the age profile of gender differentials. It is difficult to use current measures to quantify STEM career interest for younger students. Class-subject options are limited, especially for younger students, and students are incentivized to perform well in classrooms and on standardized exams to satisfy college admission boards. To overcome these limitations, a dataset of high school and middle school science fair projects and use project choices of over 17,000 students to measure gender gaps. Found that, large gender gaps favoring males in technology, engineering, and mathematics fields that increase across age. For example, the gender gap among middle school math participants is 34 percentage points, increasing to 40 percentage points in high school. Similarly, the gender gap among engineering participants increases from a substantial 26 percentage points in middle school to 29 percentage points in high school.