Centrosome dynamics is essential in mitosis. In eukaryotic cells, the mitotic spindle forms during cell division and ultimately separates the chromosomes into the daughter cells. The position and orientation of the division plane, which is of fundamental importance for proper growth and development, are regulated by the spindle’s position and orientation. Experiment has shown that pulling forces upon centrosomes from cortically anchored motor proteins drive spindle positioning and dynamics in cells. Here, we developed a coarse-grained model of the spindle, which accounts for the dynamics of microtubules nucleating from centrosomes and their interactions with motor proteins localized on the cell cortex. Our model quantitatively explains observed spindle dynamics in C. elegans embryos, such as elongation, asymmetric positioning, and oscillation. It also quantitatively predicts the scaling of these traits with cell size. This is a collaboration with Reza Farhadifar and Michael J. Shelley at the Center for Computational Biology, Flatiron Institute.