diff --git a/README.md b/README.md
index 87e20f4..dd0f30e 100644
--- a/README.md
+++ b/README.md
@@ -43,17 +43,23 @@ Install [uv](https://docs.astral.sh/uv/getting-started/installation/) (a fast Py
 uv sync
 ```
 
-This creates a `.venv/` virtual environment and installs all dependencies from the lock file. To run scripts:
+This creates a `.venv/` virtual environment and installs all dependencies from the lock file.
+
+**Note:** On Apple Silicon Macs, PyTorch GPU acceleration (MPS) works out of the box. On NVIDIA GPU machines, the default `uv sync` install may be CPU-only and you need to reinstall with CUDA support. See [PYTORCH.md](01-nanogpt/PYTORCH.md) for troubleshooting and device-specific instructions.
+
+`cd` into the section directory before running scripts or notebooks, since they reference local data files:
 
 ```bash
-uv run python 05-neural-networks/nn_torch.py
+cd 05-neural-networks
+uv run python nn_torch.py
 ```
 
-Or activate the environment directly:
+Or activate the environment and run directly:
 
 ```bash
 source .venv/bin/activate
-python 05-neural-networks/nn_torch.py
+cd 05-neural-networks
+python nn_torch.py
 ```
 
 ## License