Lullia Circles Set - Educational Stacking Toy for Cognitive Skills

It is a device made of several circles of different diameters strung on a common rod (pyramid-like). At the top of the rod a sector-arrow is set, consisting only of a triangle with an empty centre, which in size can unite one sector each of all the circles. All circles are divided into the same number of sectors. The circles and the sector-arrow are movable. Free rotation of all parts leads to the fact that under the sector-arrow there are certain sectors on each of the circles. Lullius' circles are a universal didactic tool that helps to form children's thinking processes.