GA flight instructor reported an airborne conflict while on downwind.

Attributes
ACN	1502812
Time
Date	201712
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Luscombe Model 8/Luscombe 50
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Flight Plan	None
Aircraft 2
Make Model Name	PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Person 1
Function	Instructor Pilot Flying
Qualification	Flight Crew Sea Flight Crew Glider Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 75 Flight Crew Total 7600 Flight Crew Type 500
Events
Anomaly	Conflict Airborne Conflict

Narrative:

I was flying with student advising of route I wanted him to fly during his supervised solos. Since wind was calm I had him depart; circle to west about three miles; re-enter pattern on 45 to downwind; execute an approach and land. He would then taxi to the end of runway xx and repeat the above per my clearance.we enter the downwind and he clearly announces doing so. I then noticed a piper cadet about 3 miles to southeast in a descent toward our airport. By the time we reach midfield the cadet was at our altitude and cut across around midfield heading right to us. I deviated right out of pattern and circled back onto downwind and which time the cadet was about 2 miles to the southwest and then headed directly to ZZZ1.after contacting the ZZZ1 tower the chief noted the aircraft came from a local flight school. The manner in which the flight was flown looked as if an instructor was practicing simulated engine failure with a student but no talking on ZZZ CTAF.

Original NASA ASRS Text

Title: GA Flight Instructor reported an airborne conflict while on downwind.

Narrative: I was flying with student advising of route I wanted him to fly during his supervised solos. Since wind was calm I had him depart; circle to West about three miles; re-enter pattern on 45 to downwind; execute an approach and land. He would then taxi to the end of runway XX and repeat the above per my clearance.We enter the downwind and he clearly announces doing so. I then noticed a Piper Cadet about 3 miles to SE in a descent toward our airport. By the time we reach midfield the Cadet was at our altitude and cut across around midfield heading right to us. I deviated right out of pattern and circled back onto downwind and which time the Cadet was about 2 miles to the SW and then headed directly to ZZZ1.After contacting the ZZZ1 tower the chief noted the aircraft came from a local flight school. The manner in which the flight was flown looked as if an instructor was practicing simulated engine failure with a student but no talking on ZZZ CTAF.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.