I first wrote this textbook in 2015 for a tenth grade English class in Japan. My students are planning to study abroad in eleventh grade. A good way to learn to do math in English is to do math in English. Topics should be accessible but engaging. So, we make tangents into gambling, game theory, computers, art, and elsewhere if we like.
Many people helped me brainstorm and proofread. Marjorie Carlson, Adam Pearson, Meghan Sahara, Andrew Leung, and Betsy Perkins helped out a lot. I majored in math in college, and much of the love I have for the subject comes from those wonderful professors and classes. On the pump.io network, Efraim Flashner, JanKusanagi, and Stephen Sekula offered support and suggestions.