3D geometry is a theme within spatial and geometrical reasoning. Links to relevant activities and resources are on the right hand side of this page.
Just as plane geometry is concerned with 2D objects, three-dimensional (3D) geometry deals with solids such as polyhedral and spheres, plus objects such as lines and planes in three-space.
While young children might learn to recognise and name some 3D objects, later progression might be in terms of 2D representations of 3D shapes, possibly with some 3D coordinate geometry and some 3D applications of the Pythagoras Theorem.
Even as digital technologies are beginning to be used for 3D geometry, the conundrum is being raised of interpreting 3D geometry on a flat (2D) computer screen. The development of 3D displays, either screen or projected, opens up new but as yet unexplored possibilities for geometry education.