A few pieces of the Chariot Wheel quilt block are small, but they're all straight-sided -- you don't have to fool with triangles. Most of the quilt block is assembled using strip piecing methods, so it should go together pretty quickly. One thing -- sewing an accurate quarter-inch seam is important to the success of this (and most other) quilt blocks. If you're not sure your seam is accurate, brush up on your skills before you begin.
The Chariot Wheel quilt block finishes at 12" square.