Curriculum learning changes the order of pretraining data, but it remains unclear how ordering changes the learning dynamics. We pretrain models from 14M to 1B parameters for 300B tokens under three linguistically motivated curricula--Age-of-Acquisition, word frequency, and Verb Variation (VV)--and compare each against Random ordering. We analyze latent training phases, gradient noise scale (GNS), and the singular-value structure of the output head. We find that training follows a shared sequence of latent phases, while curricula mainly change time spent in each phase. Random ordering yields higher GNS at 14M-70M and late singular-entropy spikes up to 160M, consistent with noisier gradients and output-head saturation. A reverse-order VV control shows that direction matters: descending order loses much of the accuracy advantage of the ascending curriculum. At larger scales, these stability differences are smaller. These results indicate that the curricula studied here are associated with more stable within-phase training in smaller models rather than with the creation of new phases.