Like Active Calculus - single variable, Active Calculus - multivariable is designed to support an active learning approach in the third semester of calculus, including more than 100 activities and 300 exercises. In the HTML version, more than 200 of the exercises are available as anonymous interactive WeBWorK exercises. The bound, print version for sale on Amazon is in black and white to keep costs low; the electronic versions are full-color. Thanks to David Austin, the text offers beautiful full-color graphics that are often in 3D.
Each section of the text has at least 3 in-class activities to engage students in active learning. The section on first-order partial derivatives is representative of the organization and style of other sections in the text: a brief introduction together with a preview activity, followed by a mix of exposition and several more activities. Each section concludes with a short summary and exercises; the non-WeBWorK exercises are typically involved and challenging. More information on our goals and the structure of the text can be found in the preface.
Active Calculus - Multivariable was first made publicly available in 2015. The text is free and open-source; the source code can be found on GitHub.
2020 UPDATE: Mitch Keller and Nick Long have written materials on vector calculus to extend Active Calculus - Multivariable. These draft materials are ready for classroom testing. Please read the vector calculus preface if you are interested in learning about this addition. To submit feedback on the vector calculus chapter, please use this Google Form. Like the other version of the text, the source code can be found on GitHub.