A two- to 24-item sort of anodized aluminum pieces. A difficult task requiring attention to three relevant dimensions: color (silver and gold), shape (circle, square, rectangle and hexagon) and thickness (thin, medium and thick). Many variations are possible, including: sort by shape only, shape and color, color only, color and thickness, and many more.

Includes 120 aluminum pieces and all bins. Also includes step-by-step instructions and data sheets.