Learn // Topics

All topics

Search by name, or narrow by subject, age, and type. Open a topic to see the ages it covers, what to learn first, and where it leads.

4 topics

By subject and area, youngest first

  • Electronics // Circuits

    Complete circuits

    Electricity flows only around an unbroken loop from one side of a power source, through components, and back to the other side. A switch works by opening and…

    Ages 8 to 11Concept

  • Electronics // Circuits

    Current, voltage and resistance

    Voltage is the push from the source, current is how much charge flows each second, and resistance is how strongly a component limits that flow. Turning up the…

    Ages 11 to 14Concept

  • Electronics // Circuits

    Ohm's law

    For a resistor, voltage equals current times resistance (V = I × R). Rearranging it gives the current a circuit will draw or the resistor a part needs.

    Ages 12 to 15Method

  • Electronics // Components

    Light-emitting diodes

    An LED lights when current flows through it one way, from the longer leg to the shorter. It needs a resistor in series so the current stays small enough not to…

    Ages 11 to 14Method