If you've scheduled classes in Zoom and enabled the 'meeting room' feature, you can also customise it with your own logo.
Go to Zoom.US
Click on My Account
Choose 'Settings' > 'Meeting'
Scroll down to 'Waiting Room Options'.
Select 'Edit options' and choose 'Everyone' and 'continue'
Select 'Customize waiting room'.
Click the + sign and select a logo from you files.
Click the pencil icon and update your holding message.
Click on the blue 'add waiting room description' and add in a short welcome message.
When parents join, they'll then be greeted with something like this!