Trigonometry and the World Water Crisis

If students are asked, "What is the world water crisis?" how would they respond? In the authors precalculus classes, this question is often met with blank stares and students avoiding eye contact. Many students are unaware of the world water crisis--what it is, why it is, or who it affects. Even fewer realize the utility of trigonometry for solving some of the design problems that can make clean water more accessible to more communities. The author created a trigonometry unit, which is presented in this article, to educate students about the world water crisis while also teaching them about trigonometry. Students practice right-triangle trigonometry and learn the law of sines and the law of cosines while engaging in rich problem-solving tasks that reference the world water crisis. Students engage in real-world problem-solving activities that access 21st-century skills while learning mathematics.