Can you design a container that keeps an ice cube from melting for at least 30 minutes?
Gather information: For this challenge, 1 small container will be your base. You’ll decide what materials to put inside of the container to keep it cold in there—this is known as insulation (“in-suhl-AY-shun”). After you build your design, you’ll test it by putting an ice cube inside of the container for 30 minutes and seeing how much it melts compared to an ice cube without insulation.
Think about other things you’ve seen that keep food cold on the go, such as lunch boxes, coolers, and thermoses. (See “Food for Thought” at the bottom of this page for more information.) What materials are they made from? What other properties or characteristics do they have?
Brainstorm your design: What materials will you use for your insulation? You can use as many materials as you like, as long as they fit inside your container and leave room for 1 ice cube. Think about:
Build your design: Place your insulation materials inside of 1 container—don’t forget to leave room for the ice cube. Will you add insulation to the lid of the container? What materials will you use?
Test your design: Place 1 ice cube inside the container with your insulation. Place second ice cube in second container (without insulation). Cover containers with lids. Set containers aside in a warm, sunny location for 30 minutes.
Ice cubes in a glass melt a lot faster than ice cubes inside a thermos or cooler. Why? The biggest difference between a glass and a thermos is insulation. Insulation is any material that slows the movement of heat—it helps keep cold things cold (and hot things hot). Heat in the air moves more slowly through the insulation in the walls of the thermos than it does through the walls of the glass, which means the ice cubes stay colder and melt more slowly inside the thermos.
Why is that? One of the best insulation materials is air. Heat moves slowly through air, especially when the air is trapped inside of another material. Think about a cozy down jacket—a layer of fluffy down between two layers of fabric. Little pockets of air trapped inside the down slow the movement of heat from your warm body into the colder surrounding air.
Materials with air trapped inside, such as foam, are often good insulators. The walls of thermoses and coolers are often made of a hard plastic shell surrounding a layer of foam insulation. But you can also trap air using other materials: Shredded, crumpled, or fluffy materials create pockets of trapped air that slow the movement of heat.
Test out different insulation materials in your design. Which ones are best at keeping the inside of the container—and the ice cube—cool?