Number your breadboards, Number 1 and Number 2. Insert the toggle switch into breadboard Number 1. Wire one end of the toggle switch to the breadboard's power bus.
Insert the 1,000 ohm resistor into breadboard Number 1. Wire one end of the resistor to the unconnected end of the toggle switch.
Insert the light emitting diode into breadboard Number 1. Wire the LED's anode (the positive longer lead) to the unconnected end of the 1,000 ohm resistor. Wire the LED's cathode (the negative shorter lead) to the breadboard's ground bus.
Tape the 3-volt battery onto breadboard Number 1. Wire the positive terminal of the battery to the breadboard's power bus. Wire the battery's negative terminal to the breadboard's ground bus
Insert the light phototransistor into breadboard Number 2. Wire the emitter lead of the phototransistor (marked on the phototransistor) to the breadboard's ground bus.
Insert the 5,000 ohm resistor into breadboard Number 2. Wire the phototransistor's other lead (the collector) to one end of the resistor. Wire the other end of the resistor to the breadboard's power bus.
Insert the transistor into the breadboard Number 2. Wire the transistor's collector to the breadboard's power supply bus. Wire the transistor's base to the phototransistor's collector.
Insert a LED into breadboard Number 2. Wire the LED's anode (the positive longer lead) to the transistor's emitter. Wire the LED's cathode (the negative shorter lead) to the breadboard's ground bus.
Tape the 5-volt battery onto breadboard Number 2. Wire the positive terminal of the battery to the breadboard's power bus. Wire the battery's negative terminal to the breadboard's ground bus
Position the two breadboards so that the LED on breadboard number one will direct light onto the photoreceptor on breadboard Number 2. Switch the toggle switch on and off and observe that the LED on breadboard Number 2 turns on and off.