CMB requires students to complete one term of teaching as a GSI (Graduate Student Instructor). Students can also choose to pursue an optional Graduate Teaching Certificate, which is organized through the Center for Research on Learning & Teaching (CRLT). All GSI positions should be approved through CMB before the student accepts the position, since CMB needs to coordinate the GSI appointment with the student's current funding. Per the Graduate Employee Organization (GEO) rules, teaching should be a paid position, not volunteer.
Below is a downloadable Excel spreadsheet of former GSI positions, and contact information for each.
IMPORTANT: Some funding sources have limits to how how many hours per week you can teach while on them. F31s/F30s and training grants, for example, allow no more than 10 hours/week of teaching (or 25% effort). It is important you a) ask the department who is offering the position, the effort level or hours per week, of the position, and b) coordinate this with CMB before accepting a position.