Professor Sabine Petry from Princeton University recently visited the Lower Elementary classroom to do an exciting science experiment. Professor Petry is an Associate Professor of Molecular Biology and the mother of three students at Princeton Montessori School, Audrey (UE), Elliot (LE), and Oliver (Toddler).
Her presentation was designed to educate students on the transformative effects of liquid nitrogen and she concluded by making fresh and delicious ice cream. Liquid nitrogen is the liquid form of nitrogen gas. At extremely low temperatures, nitrogen gas condenses and turns into a clear, super-cold liquid that can freeze things very quickly. She showed the class by experimenting with different objects, and putting them into the liquid nitrogen to see what would happen. She added a banana, rubber band, bouquet of flowers, a squishy toy, and an inflated balloon! 
Stressing safety, Professor Petry showed the students how the colorless, odorless liquid appears to bubble and boil as vapor mist swirls and dances at room temperature. After mixing up the ice cream base the magic happens. She explained to the students how the liquid nitrogen vaporizes after interacting with the sugar, cream, and vanilla extract. The result creates a very foggy and steamy look, creating ice cream made fresh and delicious by the miracle of science.
