In this lesson on design and technology, students learn about the behavior of voltage and current in series and parallel circuits. In a series circuit, components are connected in a line, sharing the voltage; thus, each of the three 3V bulbs connected to a 3V battery receives only 1V and will turn off if one bulb is removed. In contrast, in a parallel circuit, each bulb is connected directly to the power source, receiving the full 3V, allowing the bulbs to remain lit even if one is removed.