GFK Local Controller reported of an unsafe operation due to a student pilot not following directions. Student pilot turned to follow another aircraft not the one directly in front. The reporter also stated a possible language barrier as a problem with the student pilot.

Report 1 | Narrative: North traffic was in effect with a light northwest wind (300/08). Two to three aircraft were in the pattern for both Runways 35L and 35R. Aircraft Y executed a go-around for Runway 35R; at which time I informed the pilot I would call their crosswind. Aircraft X; a student solo pilot; was next for Runway 35R; and they also performed a go-around. I instructed the student solo to continue following the Skyhawk ahead. The student read back their instructions. Aircraft Y was then instructed to follow another C172 entering the downwind. At this point; I shifted my focus to Runway 35L in order to issue exiting instructions and sequence aircraft to that runway.

While turning back to scan the upwind of Runway 35R; I immediately saw Aircraft X in a tight downwind turn; with Aircraft Y further east; flying towards Aircraft X. I issued a right turn; northbound to the student pilot in Aircraft X; intending to re-enter the aircraft in to the upwind. While reading the instructions back; the student pilot began a left turn towards Aircraft Y. I reissued my instructions to the student pilot in Aircraft X; further emphasizing a right turn; northbound. Aircraft Y was able to see the traffic and used evasive maneuvers to separate themselves from Aircraft X.

After the student pilot in Aircraft X finally began their turn to avoid Aircraft Y; I instructed Aircraft Y to continue downwind for Runway 35R.Aircraft X required a third instruction to fly northbound as they started flying westbound. This student pilot was then issued a right turn to re-enter the downwind for Runway 35R. After their crosswind turn; Aircraft X was on a southwesterly course which required another instruction to have the student fly southbound for the downwind. Aircraft Y was reissued a landing clearance for Runway 35R.

After verifying that Aircraft X saw the traffic to follow; they were also given a clearance to land.The aircraft were in a close proximity when actions were taken. By observation from the tower; it appeared the two C172's were approximately 200 ft apart vertically and less than 1/4 mile.In my opinion; I provided easy to understand instructions in order to provide more separation to aircraft that were not in conflict at the moment. When the student pilot began a turn in the opposite direction they were instructed; it exacerbated the problem further. The student pilot also deviated from my original instructions by not following their traffic.

Due to a high volume of foreign student training at GFK; there is possibly a language barrier which may have played a role in this event.

Report 1 | Synopsis: GFK Local Controller reported of an unsafe operation due to a student pilot not following directions. Student pilot turned to follow another aircraft not the one directly in front. The reporter also stated a possible language barrier as a problem with the student pilot.