The following instructions are for the Self-Registration method only. ClassLink users will need to add co-teachers via their ClassLink data.
To add a co-teacher to your class, login at BigIdeasMath.com, click your name in the top-right corner of the site, and select Class Management. Click View on the class to which you would like to add the co-teacher.
In the class details, click Add additional teacher. This opens a search box where you can find all registered teachers in your district.
Select the teacher, and click Add co-teacher. The co-teacher will now have full access to your class.