In this apparatus, a ball fits easily through the matching ring when they are both at room temperature. However, when the the ball is heated in a flame, thermal expansion causes the ball to not be able to fit through the ring.
SIUE STEM Resource Center
http://www.siuestemcenter.org/
Southern Illinois University Edwardsvillehttp://www.siuestemcenter.org/
Science East, Room 1276
Edwardsville, IL, 62026
USA
618-650-3065