The new approach to teaching science presented by the Next Generation Science Standards (NGSS) warrants training high-quality science, technology, engineering, and mathematics (STEM) teachers to prepare the future STEM workforce. We share the implementation of an energy lesson using a nanoscience approach, well-aligned with the NGSS vision, in a secondary-STEM-education course for preservice science teachers. First, we engaged preservice teachers in discussions related to alternate sources of energy; this was followed by a case-study approach to illustrate a real-world problem of energy deficiency and solar energy (solar cells using nanoparticles) as one potential solution because it is cost-efficient, clean, and a renewable source of energy. Preservice teachers conducted several hands-on explorations in groups using real cube models to understand and illustrate the size-dependent nature and dimensions of nanoparticles, used lasers and visuals of a UV-vis spectrum, and observed the trends in voltage and current outputs for fluorine-doped tin oxide electrodes with and without nanoparticle solution. Formulating evidence-based explanations, students summarized their findings as a case-study report regarding the nanoparticle approach as a remedy to the energy-deficit problem. The lesson provides opportunities for preservice science teachers to develop an understanding of green energy and illustrates how the NGSS standards can be tied together in a science lesson.