What just happened here?

O’Shaun McGary, 10, reacts as Southview High science teacher Sarah Gladieux uses the heat from her hands to expand air in a balloon that had shrunk when covered with liquid nitrogen during the first STEM — or Science, Technology, Engineering, and Mathematics — night at Glendale-Feilbach Elementary School in South Toledo. Co-organizer Shannon Gladieux, who teaches fourth and fifth-grade math and science at the school, said about 150 children participated Wednesday in the several