. Imagine testing glass by throwing chickens at it? Sometimes fast moving airplanes fly through flocks of birds. If the birds hit the windshield of a plane, the glass could shatter and cause a crash. Airplane manufacturers have made a chicken cannon that fires rubber chickens at glass windshields. If the windshield doesn't break when the rubber chicken hits it, the designers know that the glass can withstand the force of a real crash.
A. How birds cause airplane crashes.
B. Birds are dangerous.
C. Glass is not strong enough to stop birds.
D. How a chicken cannon tests glass.