Dynamic Algebra is "doing algebraic calculations on a computer by direct manipulation". We have implemented Dynamic Algebra in the Epsilonwriter application. For that purpose, a "Theory of Movements in Formulas" (TMF) has been elaborated. It describes, in a precise context, how we can move a sub-expression in a formula with preservation of equivalence. It has been implemented in Epsilonwriter for the Pedagogical Dynamic Algebra mode. Dynamic Algebra in Epsilonwriter has other modes with more

more »

... plex actions of different classes: equivalent drag & drop internal to a formula, external drag & drop, on click calculations and rewriting rule application. This makes Epsilonwriter a very powerful and flexible calculation tool for step by step calculations; and a tool able to provide explanations. Epsilonwriter contains different options to control the possible movements and the feedback on them. It has been developed to help students learn formula structure and transformations, and to help every user produce step by step explained calculations.