Yes - you can invite all of your students and teachers at once using the Upload invitation list feature. In order to do that, please create a .csv list of your students or teachers. The list should include name, email headers, their names and emails separated with a coma or with a semicolon. You can also create a list in Excel/Numbers and export it as .csv file. Here you can find an example of a CSV list.
When your list is ready, log in to Discover with your Admin account, tap on your profile picture in the top right corner of Explain Everything Discover and go to the Account Settings. Scroll down to the Invite users section, then tap Upload invitation list for students/teacher and upload your list. After the list is loaded, a pop up message would appear asking if you want to send the invitations to the emails listed. You can also send them later by selecting Send emails.
The invitations sent to already existing non-sponsored accounts would be automatically accepted.
After the list is uploaded, you can check the current status of the invitations and what display names the accounts have been activated with. You can also generate a new CODE for the given invitation and also delete the invitation. Please note that deleting an active invitation will not result in removing the account from your subscription.