Teachers are not only required to teach knowledge to students but also skills. Among those demanded in the current era are critical thinking skills, where when students see a problem they are able to solve it and are able to remember what the problem is, how to solve it, and what the results might be. Classroom learning will be interesting and able to train student critical thinking skills if they are taught how to conduct research starting with simple stages to find a conclusion or knowledge. Departing from this, learning by using the method of discovery learning takes a large role with the concept of discovery which is the basis of the method to train student critical thinking skills.