(Citations and punctuation omitted.) Payne v. State, 219 Ga. App. 439, 440 ( 465 S.E.2d 724) (1995). The record, including Saye's testimony at the hearing on his motion to withdraw plea, demonstrates that his waiver was knowing and voluntary, and the trial court's decision finding that Saye properly waived a jury trial is not clearly erroneous.

(Citations and punctuation omitted.) Payne v. State, 219 Ga. App. 439, 440 ( 465 S.E.2d 724) (1995). The State demonstrated by extrinsic evidence, including Whitaker's own affidavit detailing discussions with his trial counsel and his testimony at the hearing, that the waiver was knowing and voluntary, and the trial court's decision finding that Whitaker properly waived a jury trial is not clearly erroneous.

Here, the State has filled an incomplete record with extrinsic evidence adequate to show that its burden was met. See Payne v. State, 219 Ga. App. 439 ( 465 S.E.2d 724) (1995); Evans v. State, 216 Ga. App. 21, 24 (3) ( 453 S.E.2d 100) (1995); compare McCormick v. State, 222 Ga. App. 753, 754 (1) ( 476 S.E.2d 271) (1996). 3.

In addition, Seitman is well-educated and holds a college degree. See Payne v. State, 219 Ga.App. 439, 440, 465 S.E.2d 724 (1995) (trial court's determination that defendant understood right to jury trial not clearly erroneous in light of defendant's high school diploma and two years of college). Seitman also testified that she had been summoned to jury service, had been through the voir dire process, and had actually served on a jury.