Strategic knowledge is fundamental in order to become adaptive. Though it is crucial in factorization of polynomials and polynomial-equation solving, it is hardly ever taught in school. Aplusix, an ICAI system, tries to deal with this aspect. Aplusix can be either example-driven or reasoning driven. In the first case the problem is solved by the system. However, the student may ask for explanation concerning facts or strategic knowledge. In the second case, the problem is solved by the student. He chooses among the possible transformations and the system performs the necessary computations. The goal of Aplusix is to help the student to discover how to perform the necessary matching operations and to develop efficient strategies. In order to do so, the system shows all the operations performed, including backtracking, when presenting the examples. When solving the equations with the help of the system, the student is relieved of the burden of computation. He can therefore use all his resources on the task of reasoning. This paper describes the problem-solving component of Aplusix and its explanation module.