Cessna 150
Flight Crew Instrument; Flight Crew Commercial; Flight Crew Flight Instructor
Flight Crew Last 90 Days 76; Flight Crew Total 887; Flight Crew Type 97
Aircraft Equipment Problem Critical; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway
General None Reported / Taken
Aircraft
We were practicing touch and go's and at the last landing we tried to brake the aircraft and I felt that the left brake was not working.  I communicated to the Tower that I could not turn to the left so they cleared me to turn to the right.  I cleared the runway on taxiway Alpha and I tried to stop the aircraft but we couldn't and we did the full stop at the grass. We didn't hit any light or nothing to be considered damaged. Airport operations went to the place and they saw that everything was good.
C150 flight instructor reported during touch and go training with student; there was brake failure after landing.