but could I interrupt the ground connection from the Arduino to the battery with the switch, joining each pin to ground and the left and right ones to a digital pin for input?
When you flip the switch it completes two separate circuits?
MichaelMeissner - I assume this is the type of switch JimpboZA suggested and confirmed my assumption on how it works. Many thanks. I need a switch that locks into place so the Arduino remains on continually until the switch is flipped off. I've read about the Arduino sleep function, thanks for the link I'll look into it further as another option.
I assume this is the type of switch JimpboZA suggested