In order to search by custom user attributes, you’ll go to the Dashboard -> Users -> Then type the attribute value into the search bar. This will filter your user list accordingly.

Note: This search function also encompasses the users’ names as well, so it is best to make sure your user attributes are less likely to overlap with user names. For example, when putting the homeroom teachers’ names in as an attribute, include a title such as Mr., Ms., Dr., Etc.