Hello ipadteaching,
Thank you for using Apple Support Communities.
We understand that you are having an issue with the Apple Pencil strokes disappearing as you write on your iPad. It appears that the issues seems to occur on one area of the iPad, but not another. You have tried using the pencil with your palm touching and not touching, as well as turning the Zoom accessibility function off, without affecting the issue. Does the same issue occur when you try to draw or write using your finger? We would suggest you try resetting iPad's settings in Settings > General > Reset > Reset All Settings. Be certain you do not select Erase All Content and Settings as this will erase all of your information. It is a good idea to perform a backup of your iPad prior to resetting its settings.
Best regards.