In this chemistry lesson, the topic of electrolysis is introduced, focusing on the behavior of electric currents in circuits. The lesson explains the concept of conductors and insulators, using a simple circuit with a battery, bulb, and graphite rod to demonstrate how electricity flows when the circuit is complete, causing the bulb to light up. The flow of electrons as a current, leaving from the negative terminal and returning to the positive terminal of the battery, is detailed, highlighting the role of materials like copper and graphite as conductors.