Due to GDPR you will not be able to download login slips with existing passwords for your students. However, you can regenerate new passwords and download the login slips. These will have your students' existing username and new passwords on them.
To do this, login to the Teacher Dashboard and follow these steps:
Manage > Students
Select the class
To regenerate login slips for the whole class, select the top most tick box and a little tick will appear next to all students' names. If you wish to download the login slip for just one child, just tick the box next to that child's name.
In the Action menu at the top of the page you will then see an option to Regenerate Passwords / Login Slips. Select Apply.
You will then have an option to reset and regenerate passwords so they are different or give every child the same password.