Elias stretches a rubber band and lets it go. The rubber band flies across the room. Elias says this demonstrates the transformation of kinetic energy to elastic potential energy. Is Elias correct?

No, he is not.

Explanation:

When he let the rubber band go, the band compresses, so there's elastic potential energy in it, which will be transformed into kinetic energy when it gains velocity and flies across the room.

Then, Elias had inverted the concepts: the experiment demonstrates the transformation of elastic potential energy to kinetic energy.

No, Elias is wrong

Explanation:

Kinetic energy of an object is the energy the object possesses when it is in motion. Examples include a ball in motion, a moving car and a swinging pendulum. While potential energy of an object is the energy present in the object at rest. Examples include a ball at rest and a stationary car.

When the rubber band is stretched, the type of energy in it, as a result of the force applied, is called elastic potential energy while the energy in the rubber band while flying across the room is kinetic energy (as defined earlier).

Hence, Elias was wrong as the transformation is from potential energy to kinetic energy and NOT the other way round.