The students are given a list of 30 equations. 10 of them are classified as short basic equations, 10 as long basic equations, 10 as advanced equations. Each correct short basic equation gives the students 1 point, each long basic equation 2 points, and each advanced equation 3 points. Each student has to choose 10 equations from this list, in order to get a minimum number of points that will be increased by the teacher day by day, according to the previous result of each student. In the first days, the students will try to stay in their “comfort zone”, without facing the advanced equations. Once they get familiar with the easy exercises, they will start trying the difficult ones. This is an individual activity, but, once the students check their results and get their score, they work in pairs in order to correct their mistakes and to try to understand how to solve the equations they did not pick because they considered them too difficult to solve