6external parts or peripherals of a computer system and identify which are output and which are input devices.

A computer peripheral, or peripheral device, is an external object that provides input and output for the computer. Some common input devices include:

keyboard
mouse
touch screen
pen tablet
joystick
MIDI keyboard
scanner
digital camera
microphone

Some common Output Devices : 
monitor
projector
TV screen
printer
plotter
speakers

Mouse keyboard speakers headphones 

There are lots of different peripherals of computer systems. Some examples are listed below:

Input:
Keyboard
Mouse
Video Camera
Microphone
Joystick
Scanner

Output:
Monitor
Projector
Printer
Speakers

Any external device that gives input to or gets output from the computer is a peripheral.

There are many peripheral devices but heres 4 external output ones: monitor, speakers, plotter, and printer. Here are also 4 peripheral input devices: mouse, keyboard, mousepad, and joystick.

Monitor, Output,
Printer, Output,
Mouse, Input,
Keyboard, Input,
Scanner, Input,
Microphone, Input,
Speakers, Output 
E.T.C

1.) keyboard - input

2.) mouse - input

3.) printer - output

4.) monitor - output

5.) speakers - output

6.) microphone - input

Keyboard-Input
Mouse-Input
Monitor-Output
Speakers-Output
Printer-Output
Hard Drive-Output

Mouse - Input
Keyboard - Input
Audio - Output
Monitor - Output
A joystick or controller - Input

That's all i can think of.