Stanford CS312 quiz: what happens if you pin the residual stream's RMS mid-training?

tatsu_hashimoto · x · 2026-11-13

A prediction quiz from Stanford's CS312 "Deep Learning Alchemy" tests intuition on how residual connections and layer norms interact during training. Setup: train a 35M-parameter, 8-layer Transformer LM for 9,375 updates, then fork at step 4,688 into two runs. Control continues normally; in the modified run, after every attention/MLP residual addition, activations are rescaled to match the RMS measured at the fork point (targets from 16 validation sequences, then frozen — post-norm-like scaling with no mean-centering or learned gain).

Answer options range from "improves by >0.02" to "worsens by >0.15 or divergence," forcing you to reason about how the residual stream's scale drifts during training and whether freezing it breaks downstream layer adaptation.

Related event: Freezing Residual Stream RMS Mid-Training Barely Hurts Loss(2 posts)→

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