For a light bulb to light, charge must enter the threaded side of the bulb and exit out the bottom tip of the bulb OR enter the bottom tip of the bulb and exit out the threaded side of the bulb. As long as a bulb is connected in this manner to the pathway that leads from the positive terminal of the cell to the negative terminal of the cell, the bulb will be lit.
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Know How a Light Bulb Lights
A light bulb will light if charge flows through its filament. The filament is the curled wire that is located inside the glass bulb of a light bulb. The filament is connected to the side of the light bulb by a wire that supports one of its ends. The other end of the filament is supported by a wire that leads to the bottom tip of the bulb. As long as the bulb is arranged such that charge enters its side and exits out its bottom OR enters at the bottom and exits out the side, the light bulb will light. Carefully inspect each diagram to see if the light bulb is arranged in one of these two ways.

It's All About Anatomy
Questions in Activity 3 - Wire It Up will test your understanding of the wiring of a light bulb like no other question. You must use your understanding of the anatomy of a bulb in order to determine where the second wire must be connected. After you think you have determined the locatoin, tap on the corresponding letter. Notice that a wire is drawn connected to a bulb at that location. Before you tap the Check Answer button, trace the pathway from the first wire until it exits. Remember: if charge enters the bottom tip, it will only light the bulb if it passes out the side. AND if charge enters the side, it will only light the bulb if it passes out the bottom tip. Check your answer first. Tap Check Answer second.