If you want to claim he didn't lie in court, then he's 100% guilty of lying to the FBI. I wouldn't recommend teaching either to kids.

Below are exchanges between Judge Sullivan and Flynn when he confirmed his guilty plea in court, under oath. He acknowledges he knew lying to the FBI was a crime and affirmed his guilty plea to that crime.

THE COURT: At the time of your January 24th, 2017 interview with the FBI, were you not aware that lying to FBI investigators was a federal crime?

THE DEFENDANT: I was not -- I was aware.

THE COURT: You were aware?

THE DEFENDANT: Yeah.

...
THE COURT: Do you feel that you were competent and capable of entering into a guilty plea when you pled guilty on December 1st, 2017?

THE DEFENDANT: I do, Your Honor.

THE COURT: Do you understand the nature of the charges against you and the consequences of pleading guilty?

THE DEFENDANT: I do understand, Your Honor.

THE COURT: And that was covered extensively by Judge Contreras. I've read the transcript.
Are you continuing to accept responsibility for your false statements?

THE DEFENDANT: I am, Your Honor.

THE COURT: Do you still want to plead guilty, or do you want me to postpone this matter, give you a chance to speak with your attorneys further, either in the courtroom or privately at their
office or elsewhere, and pick another day for a status conference? And I'm happy to do that.

THE DEFENDANT: I appreciate that, but no, Your Honor.