Hundreds of grassroots groups have sprung up around the world to teach programming, web design, robotics, and other skills to free-range learners outside traditional classrooms. These groups exist so that people don't have to learn these things on their own, but ironically, their founders and instructors are often teaching themselves how to teach.

There's a better way. Just as knowing a few basic facts about germs and nutrition can help you stay healthy, knowing a few things about psychology, instructional design, inclusivity, and community organization can help you be a more effective teacher. This book presents evidence-based practices you can use right now, explains why we believe they are true, and points you at other resources that will help you go further. Its four sections cover:

• how people learn;
• how to design lessons that work;
• how to deliver those lessons; and
• how to grow a community of practice around teaching.

This book is a community resource, and contributions of all kinds are welcome, from errata and minor improvements to entirely new sections and chapters. Parts of it were originally created for the Software Carpentry instructor training program, which has been run over several hundred times over the past six years, and all of it can be freely distributed and re-used under the Creative Commons - Attribution 4.0 license. Please see http://teachtogether.tech to download a digital version or purchase a printed copy at cost.

The compiler with his biggest fan, July 2018