How have courts interpreted the waiver of a defendant's right to stand trial by jury?

The rationale for strict construction of this state constitutional requirement is clear: "If the waiver were left to implication from conduct, there would be a danger of misinterpretation with respect to a right the importance of which requires there be certainty. Moreover, appellate courts would be faced with the burdensome task of determining whether the facts of the particular case warrant such an implication, whereas trial courts, without any difficulty, can eliminate doubt and safeguard the rights of both the defendant and the People by obtaining express statements from the defendant, from his attorney, and from the prosecuting attorney not merely as to whether a trial by jury is desired but specifically that a jury is or is not waived." (People v. Holmes, supra, 54 Cal.2d at p. 444, 5 Cal.Rptr. 871, 353 P.2d 583.)