I developed a simple reaction time measurement program and an external device with buttons via USB. This program was made for children specifically under age 10. In practice the children have to answer to simple question. The question is already defined and it is answered by a simple yes or no. After pressing the Start button on the external device during the initial screen the program shows different pictures. They are two types of picture series. In the first one they are pictures of animals or plants. For this series the children have to decide if there is an animal on the picture or not. In the other one there are simple mathematical equations. For this one they have to decide if the equation is true or false. The answers are made by pressing one of the two answer buttons on the external device which is connected to the PC by USB. These two buttons function as „True” or „False” for the program. This external device is implemented by a MSP430FR2433 microncontroller. The microcontroller measures the reaction time for each picture and if the question was answered correctly or not. The program writes out the average and deviaton for every reaction time combined.