The Mathematics and Pattern Gallery is a key component of the new Waterloo Regional Children’s Museum. The gallery provides immersive open-ended play based on systems of geometry. A huge translucent screen and geodesic skeleton arches over one side of the central museum atrium, supporting shadow-play and kaleidoscope projections. The screen shelters a landscape of shaped risers that make a dispersed ‘archipelago’ of islands running through the main gallery level. A variety of geometry and construction toys are located on these surfaces. Large-scale construction toys have been specially engineered for the exhibit by PBAI in collaboration with Roylco, a Canadian toy manufacturer. The equipment includes three-dimensional lattice systems, stacking blocks based on primary shapes that unfold to display their two-dimensional geometry, and shaped tiles that explore space-filling pattern formations.