How can I add new Pupils to my classes if I'm a Teacher but not a School Administrator?
The best way to do this is to speak to your Purple Mash school administrator(s) and have them add the pupils for you. Adding new pupils (or modifying/removing existing ones) is easy for a School Admin.
The other option is to ask your school administrator to change your Purple Mash access to also be a school administrator. If they agree, then you can login and make these changes yourself.