The purpose of this study was to develop a computer-based inquiry activity to learn stimuli and response. The software to measure the reaction time can run on the Microsoft Windows operating system. With this computer program, various visual and auditory stimuli can be produced. Accurate reaction times can be instantly obtained simply by clicking mouse buttons or using a keyboard. The program contains an extra function that allows additional variables to be set. Using this function, students can perform their own experiments. Based on the developed software, computer-aided reaction time experiments were also developed. The developed experiments were related to three types of reaction time measurements: simple reaction time, discrimination reaction time and the reaction time when focusing on other ideas. 20 middle school students and 8 biology teachers tried the developed software and experiments. Most of them performed the suggested experiments effectively. Their opinions were reflected in the developed results.