As mentioned earlier, electric current in a circuit is the flow of electrons through that circuit. The flow of electrons in a circuit can do things like make its light element glow, make its motor turn, and so on. Current through a circuit is the result of an electrical pressure called Voltage, which typically has to be connected to a circuit to make the current flow.
In this activity, you will set up supply voltages on the bus strips so that sockets with supply voltages are adjacent to every terminal strip row. This will make it convenient to connect supply voltage to any terminal strip row that might need it. You will make a lot of those kinds of voltage connections to your circuits in upcoming activities.
You will also use the micro:bit running a voltmeter script to check the electrical connections and make sure each one has the correct voltage.