Dört Dörtlük Konu Pekiştirme, which was developed with the idea of “Full Topic Reinforcement”, is a mobile application that is prepared for the 9th, 10th, 11th and 12th grades of Physics, Chemistry, Biology and Mathematics. This application is a supplement to the textbooks and is intended to reinforce the topics taught in schools. The application consists of multiple-choice questions, and the questions have four possible answers. After the user has chosen the answer, it is evaluated based on the correctness of the answer and the quality of the explanation. The user can see the scorecard and the test, subject, course, class-based completion and success rates.