Zoom has the capability of allowing multiple participants to share their screen at one time. Below is a run-down on the basics, but for more in-depth information, see Zoom's how-to on the matter.
*System Requirements: Zoom web client or desktop client version 5.0.0 or higher on any OS.
*Limitations: Mobile devices/apps cannot share at the same time as others, and will only see the most recently shared screen. Therefore, this cannot be used with participants using Chromebooks.
Before Meeting
Before starting the meeting, check the Settings in your Zoom app. Make sure you have Use dual monitors selected. This will make it so you can split out the Zoom screens, keeping the shared screens on one monitor, and your student's videos on the other. It's not required, but it makes it infinitely easier to manage keeping an eye on everything going on in your virtual classroom.
In Meeting
Once you've started a meeting where you are the host, click the upwards arrow next to Share Screen and enable Multiple participants can share simultaneously.
Once you do that, students can share screens, whether they are on Zoom through a web browser or an updated desktop app. You can switch between the shared screens by clicking View Options and clicking between the names under Shared screens. Note: You cannot access this while sharing a screen yourself.