Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 62; Flight Crew Total 472; Flight Crew Type 230
Situational Awareness; Communication Breakdown
Conflict NMAC
Flight Crew Took Evasive Action
Human Factors; Procedure
The flight was a training flight; we were performing commercial maneuvers over ZZZ1 in one of the local practice areas. There was no other plane making a radio call on the practice area frequency and we did not have ADS-B in onboard.  After performing Lazy 8; I have my student level off at 3;000 ft. MSL heading southbound over ZZZ1 while I critique his performance. At that time; my student told me that he looked to the right and saw an airplane coming from that direction heading eastbound perpendicular to our flight path. My student took control and make an immediate descent to avoid a collision. We clear each other by less than 200 ft. I couldn't see that traffic approaching from the right due to my seat position and the doorpost blocking the view. I later saw that traffic after it passes our left wing. That traffic was a low-wing with dark blue color; it looks like a war bird to me. It also did not make any attempt or maneuver to avoid collision with us. I think the main causes for this event were the weather condition; a dirty windshield; and lack of ads-b traffic advisory. The sky was hazy and dark; making it hard to spot any traffic with dark color paint. The dirty windshield also contributes to that too. We also did not hear anyone making a radio call on practice area frequency even though we did that before starting the maneuver.
Instructor Pilot reported having to take evasive action to avoid a mid air collision while in a designated practice area.