Some ideas:
* Give a fraction **n/m**, prepare a pie splitted in **m** (at higher levels, a multiple of **m**), and the child has to select on the pie the good number of splits.
* Give a pie splitted in **m** with **n** selected splits and let the child input the fraction.
started in https://invent.kde.org/education/gcompris/-/tree/work/fractions_charts (addition of qml charts + first idea).
todo: check if qml charts needs to be added to the packages