For our first lab we had to wire up simple circuits to power LEDs. My main challenge was attempting to complete this lab from the comfort of my home while waiting for a package to arrive.
The lab specified that we should be using a 9 volt battery and voltage regulator to limit the voltage to 5. Seeing as I didn't have a voltage regulator, I started by using the 5 volts my arduino can generously output.
First I wired up two LEDs in series with a 560 ohm resistor. Though I only needed 150 ohms of resistance, I used the smallest resistor I had.
Then I wired up a push button:
I began to think about what simple circuits with a switches I could wire up with what I had in my house. Rather unoriginally, I figured that a door would make the perfect switch.
Since I had a 560 Ohm resistor I found a 9 volt battery and used it to power my switch circuit.