Dropdown lists can increase efficiency and help ensure data reliability.
If the Mac version isn't playing, try the Youtube link. These recordings do not have audio...yet.
The key to dropdown lists is that you need to use the absolute cell references (example: $A$1:$A$3), because you want to ensure that the list always points to the same data fields.
This dropdown list exercise was for a teaching demonstration. The PC video was recorded with Windows's X-Box recorder (Windows +G), which does not show the pop-up window for the data validation tools.