https://practicaledtech.com/2020/01/22/ethermap-streamlines-collaborative-map-creation/

Ethermap is a new tool that simplifies the process of collaboratively creating online maps. Unlike Google’s My Maps, Google Earth, or ESRI’s mapping tools, Ethermap doesn’t require user registration.

To invite others to work on your Ethermap with you, you simply have to give them the link to your map.

Google Maps & Earth – More Than Just Social Studies.
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more on Polly Google in this IMS blog
https://blog.stcloudstate.edu/ims?s=polly+google