this magformers curve 20-piece magnetic construction set contains special curved pieces like arches & sectors, so children can create special 3d structures with curved edges. all pieces are compatible with other magformers construction sets. four different shapes are included in this 20-piece set. this is a set which can be used in small groups to explain the different properties of curved edge shapes in either 2d or 3d forms & to develop children's mathematical vocabulary. multiple sets can be combined to familiarise children with symmetry, turns, or to visually explain radius, diameter & circumference as well as circles & semi-circles, arcs & other terms. various 3d models can be made with this set such as open & closed cylinders, half cylinders or cones.