Beginnr level simple lithic puzzle. A modern knapped raw piece of Oregon Obsidian was worked through the rough out stages for a Blade Core, with the early shaping flakes saved, as they might appear in the archaeological record on a production/raw material site.  This example here is a preform/rough out for a core that might provide future blades for cutting. The initial shaping flakes are saved, and all together 11 pieces to put together back to a roughed out core. When new students piece such puzzles back together, it helps them to understand how flint tools are flaked and reduced, and how each flake represents a part of the process. It also helps to identify diagnostic flakes, such as crested blade(first flake on left), broken blade removals, and intact blades with percussion bulbs and terminations. This particular puzzle represents the most simple form and example to study, and contains 10 pieces to refit.  A water soluble glue or a rubber band, or simply by hand, is a way to hold together if needed, and this process has proven to be a great aid for new archaeology students who are not yet familiar with stone tool technology.  The flakes fit back on the core only in order of their production, and therefore teaches the process.  They place together with almost molecular fit, so flush its hard to see the broken line.