What Things Allow Electricity To Pass Through Them?
Things which allow electricity to pass through them easily are conductors and those that do not allow it to pass are insulators. It is very easy to find out which objects are conductors and which are not. Make a circuit as you have done earlier, using the bulb, drawing pin etc. Remove the paper clips and in its place you should use the objects you want to check, to complete the circuit. Take metal wire, candle, wood piece, glass piece, metal keys, etc. You will see that when you keep certain objects to complete the circuit, the bulb will glow:
They would be the conductors. And when other objects are kept, the bulb will not light up. Such objects would be the insulators.
The Principle of Gears
Insert six pins each into two corks, at evenly spaced distances, in a round manner on their big flat surfaces. Insert a knitting needle through one of them and through the other. Insert a stiff piece of wire which has been bent to have a shape of a handle at one end. And both these items are ready insert their both ends into thick pieces of cardboard so that they remain steady. And then arrange both these items into a wooden frame. The pins of both corks should overlap each other. Now when you turn the handle on the second cork, you will see that the other cork is also turning. This is how the gears work.