SchoolTool’s developer mode, or “devmode,” turns on several features handy to developers, but which should not be used in production instances. These dev-friendly features include sample data generation, and web view of the error log.
To enable devmode, edit instance/schooltool.conf in your sandbox (you may have to do make instance first to generate the instance directory) and uncomment the line that says:
#devmode on
To switch back, just comment out the same line in schooltool.conf.