For Sandia materials scientist Olivia Underwood, volunteering with HMTech has been one way to make a difference in the community. This is her second year working with the program and her first year as an instructor. In her class — “What is Materials Science?” — students learned how to identify categories of materials, such as metals, ceramics, composites, polymers and semiconductors, by disassembling items like a scooter, waffle maker, handheld mixer and electric stovetop.