The common energy transformation that allows you to send a rubber band across the room is potential energy to kinetic energy.

Here's how it works:

1. Potential Energy: When you stretch the rubber band, you are storing potential energy within it. This energy is stored due to the elastic deformation of the rubber band.

2. Release: When you release the stretched rubber band, the stored potential energy is converted into kinetic energy, which is the energy of motion.

3. Motion: The rubber band moves rapidly across the room, propelled by the kinetic energy it gained from the conversion of potential energy.

So, the act of stretching the rubber band stores potential energy, and releasing it converts that stored energy into kinetic energy, resulting in the rubber band's movement.