Analysis of the simplest bi-manual tasks in various industrial concerns in the Montreal area has revealed a number of common characterisrics. These have been simulated by the construction of a device known as the Laborimeter. The basic element of this apparatus is a disc which rotates at 6 rpm and which has 20 equally spaced holes in its periphery. Into these holes, of which there are 8 exposed at any one time, are placed I.-in. diameter checker-like objects. If an incorrect placement is made, the object remains in the hole and is rotated back to S for correction. In the case of a correct placement, the object is returned into a tray immediately below S's hands, a counter is activated, and a tape is punched, the Iatter device providing a time pattern analysis. S is seated immediately in front of the Laborimeter, which may be adjusted in the vertical plane SO that his hands are level with the disc. He is instructed to take an object from the tray in each hand, placing as many as possible i n the exposed holes. Recently 12 girls and 12 boys in each of Grades I through \'Ill within the Ottawa Public School system, were given three 3-min. time blocks, with approximately 1 min. rest between blocks. The findings are summarized in Fig. 1. An analysis of variance revealed highly reliable Grade and Time main effecu (Fs = 89.46 and 76.15, respectively), no sex