  In this paper we make some considerations about using a dynamic geometry
software for teaching history of mathematica at university level. After a short
introduction to the software GeoGebra, we discuss four activities. The first is
an exploration of the menu of the tools menu following the first part of the
first book of the elements of Euclid. The second is an activity about pentagons
and pentagrams which aims at finding a more natural way of discovering their
properties than that suggested by Euclid as an illustration of the method of
synthesis and analysis. The third is an activity on circle inversion and its
connection with polarity and the construction of the fourth harmonic point
after three given point on a line. The activity continues with the reading of
Poncelet's ideas about ideal secants of conics and how to use GeoGebra to make
sense of them. The fourth activity shows how to use the possibility to move
objects in GeoGebra to make sense of the geometric intuition behind Cremona and
Hirst letters about the Bellavitis-Hirst inversion of a circle. We discuss the
reasons why we believe that these kind of activities may help students to read
and understand original writings in projective geometry and why we believe that
they may be very effective in the training of prospective teachers of
mathematics.
