In Anderson v. Mt. Clemens Pottery Co. (1946) 328 U.S. 680, employees asserted claims for unpaid overtime under the federal Fair Labor Standards Act of 1938 (FLSA) (29 U.S.C. 201 et seq.), alleging that because their employer's time-keeping system automatically reduced their clocked breaks of work in a predetermined manner, they were not fully compensated for work performed. (Anderson v. Mt. Clemens Pottery Co., supra, 328 U.S. at pp. 682-684.) Noting that the FLSA obliged employers to keep proper work records, the high court determined that once the employees had adequately shown they performed work for which they were owed compensation and sufficient evidence of the amount of that work, the burden shifted to the employer "to come forward with evidence of the precise amount of work performed." (Anderson v. Mt. Clemens Pottery Co. supra, at p. 687.) A contrary holding, the court explained, would "penalize" employees and "place a premium on an employer's failure to keep proper records in conformity with his statutory duty; it would allow the employer to keep the benefits of an employee's labors without paying due compensation as contemplated by the FLSA." (Id. at p. 687.) The Supreme Court discussed pre-shift duties and found the ones alleged were compensable. The Court illuminated: The employees proved, in addition, that they pursued certain preliminary activities after arriving at their places of work, such as putting on aprons and overalls, removing shirts, taping or greasing arms, putting on finger cots, preparing the equipment for productive work, turning on switches for lights and machinery, opening windows and assembling and sharpening tools. These activities are clearly work falling within the definition enunciated and applied in the Tennessee Coal and Jewell Ridge cases. They involve exertion of a physical nature, controlled or required by the employer and pursued necessarily and primarily for the employer's benefit. They are performed solely on the employer's premises and are a necessary prerequisite to productive work. There is nothing in such activities that partakes only of the personal convenience or needs of the employees. Hence they constitute work that must be accorded appropriate compensation under the statute. (Id. at 692-93.)