Neither rubber nor glass are good conductors of electricity. They are both considered insulators.

Here's why:

* Rubber: Rubber has a very high electrical resistance. This means it strongly resists the flow of electric current. That's why rubber is commonly used in electrical insulation, like the coating on wires.

* Glass: Similar to rubber, glass also has a high electrical resistance. It prevents the flow of electricity. That's why glass is used in electrical equipment, like light bulbs and insulators on power lines.

While neither is a perfect insulator, they are much better at resisting the flow of electricity than materials like copper or silver, which are excellent conductors.