The COVID-19 pandemic has forced educational institutions to adjust their learning process to distance education or online learning. This paper explains how to teach optics during the COVID-19 pandemic by implementing project-based learning that can be supervised online. Students are instructed to design, characterize, and optimize droplet lenses to produce the highest possible lens resolving power by using the USAF-1951 test chart. To do project-based learning correctly, students must understand various optics concepts, such as the principle behind light propagation (Fermat's principle), determining focal lengths, compound lenses, lens aberrations, and lens resolving power. This paper also describes how to optimize droplet lenses to produce high resolving power with easy to handle and inexpensive materials.