If you are any combination of parent, teacher, or administrator, you can use the same email address to switch accounts without having to login in and out. Prior to switching accounts, make sure your accounts are linked using THIS article.
Switch Accounts on mobile
Open the Playground app and click the three lines in the top left corner of the screen. Tap "Switch Account" to open the Switch School menu. Select the school or user you'd like to switch to and the app will switch accordingly.
Switch Accounts on web
Click your name in the top right corner of the screen to open the drop-down menu. Click "Switch Accounts".
The Switch Account screen will open to show your additional linked accounts. Select the account you'd like to switch to and the new dashboard will open up.