help identifiing components

I am trying to to create this freq Meter. https://www.arduino.cc/en/Tutorial/SimpleAudioFrequencyMeter

what are these components: The black circle object to on the left of the breadboard. ( I think its the potentiometer) The figure on the bottom, on the separate green board.

Another question involving the schematic: what is the three pin object located at the U1 (sleeve,right,left)thing is what is the

Thank you for your help

1.) black circle - yes pot. (says in the description) - "The 10k trimpot allows to adjust the gain of the amplifier "

2.) green board - headphone/audio jack - "Gotta have the audio source coming from somewhere" :)

3.) The audio jack (component in schematic form)