Cast from a durable mix including real stone, these large tactile stones measure 3 inches across and are designed to enable children to have sensory experiences by experimenting with raised and indented shapes and patterns. The set of 8 stones include: 4 raised/bumpy designs — circles, dots, wavy lines and a grid; and 4 indented/hollow designs — circles, lines, zigzags and a spiral. The set comes complete with a teacher's guide with ideas for sensory play, messy play, printing and mark making.