I teach curve fitting with this dataset and recently added the fifth dataset. It illustrates Simpsons paradox.
https://www.linkedin.com/posts/panela_loved-adding-ancombes-...
https://www.linkedin.com/posts/panela_loved-adding-ancombes-...
I recommend putting together the Quintet in one image, so that the original 4 charts, plus the new one are all visible and interpretable together. It will be learning aid for decades to come.