Assess students' ability to determine and justify which regular n-gons are constructible with compass and straightedge. Tasks: apply Gauss's criterion (linking constructibility to Fermat primes), give rigorous proofs using degree/field arguments or cyclotomic polynomials, design explicit step-by-step constructions for n = 3, 5, 17, and demonstrate impossibility for non-constructible n (e.g., 7, 9). Require clear geometric construction diagrams, algebraic justification, and a brief reflection on the role of Fermat primes.