Teachers are trained to plan and conduct pedagogical activities. But, as these activities become richer-i.e. more collaborative, with more open resources, and building upon an increasing number of digital tools-planning becomes increasingly important. We conducted contextual interviews with seven middle and high school teachers, about their practices in planning and conducting pedagogical activities. We found that teachers design scripts to guide them through the session and scripts for students to use independently. They adjust their scripts during a session and edit them afterward. They reuse old scripts, adapt scripts from other teachers, and from online and physical sources. We derive implications for the design of scripting tools: supporting scripts at multiple levels of detail, or annotations for adjusting scripts during and after teaching sessions.