With a little chemical investigation, you can figure out how Jet-Puffed's new color changing marshmallows work!
The importance of surface area can be illustrated by adding spherical solids at known sizes and temperature to other substances at different temperatures and then monitoring the rates of temperature changes of the system over time. Larger spheres (with less surface area per sample) exchanged heat with water more slowly than smaller spheres, and less thermally conductive glass spheres exchanged heat with water more slowly than iron spheres. Additional, more colorful demonstrations are described in which small glass spheres cool thermochromic plastic cups more quickly than larger glass spheres.
In Chemical Mystery #10, plastic straws are observed to “magically” change color when waved in the air. Check out the explanation and the video.