Arrange them in order with the best conductor first down to the poorest. You have found out that metals make the best conductors. When you used them in the circuit, the bulb glowed brightly and steadily. Sometimes, you might see the bulb flicker. That happens because some materials are poor conductors.
Poor conductors reduce the number of electrons flowing.
When the bulb does not go on at all, electrons are not moving. The wrapping that covers wires is an insulator. It keeps the electrons inside the wire, preventing accidental short circuits. That is why you must take the insulation off the ends of any wires that you are using in a circuit. Electrons can't get through u nless the ends are bare metal.