This inquiry leads students through an investigation of the South China Sea dispute, in which several nations in East and Southeast Asia are claiming ownership of parts of the sea for various purposes. By investigating the compelling question “Can nations own the sea?” students evaluate whether nations have the sovereign right to claim parts of the sea for themselves and if so, whether the rights of certain nations outweigh the interests of others. The formative performance tasks build on knowledge and skills through the course of the inquiry and help students construct an understanding of the current international laws governing the sea as well as the claims both China and Southeast Asian nations have made to the South China Sea in particular. Students create an evidence-based argument about whether nations can claim parts of the sea for themselves.