Access a second macOS desktop during keynote presentation

During a keynote presentation, how can I access a second macOS desktop during the playing of the presentation without interruption? I have my presentation on one desktop, the slides showing on an hdmi connected projector and an open desktop (Desktop 2) with my email open. Every time I move over, the keynote presentation cuts to the wallpaper and goes away.

I’m a school teacher and it would be helpful to access my email on a separate screen during a keynote presentation while students take notes for a moment. When I try, the presentation goes away.