I looked around and found this guide by MAA: https://www.maa.org/programs-and-communities/curriculum%20re... It's not specifically active learning, but has lots of good classroom tips.

I also found this blog post series: https://blogs.ams.org/matheducation/tag/active-learning-seri...

Yes, ivan_ah is right, that's the book I meant. Free and evidence-based. I'd say active learning is baked into pretty much all the chapters of the book, because the evidence is very strong that this is the best way to go.