There are two sites where people can find, use, and make and share visual, interactive math activities: Geogebra and Desmos. With my finite time and so many pots on the fire, I decided in January that I'd get to know Geogebra, primarily because it is more officially and formally OER; pretty much everything is CC-BY.
While there are some tutorials it's not really easy to figure things out (it was weeks before I found out that I could click on any app in the right place and find the "construction protocol," which lists the steps the author did to create the app)... but I found this
https://www.geogebra.org/m/k55KxaVx#material/hpuY9TtF
where students place assorted numbers in scientific notation on anumber line. I modified it for students who need fluency in understanding negative numbers... so they can automatically "feel" that -10 is lower than -1...
https://www.geogebra.org/m/T9jPesSF
I've had lots of great help from folks on twitter -- including one Steve Phelps who sent me screencast how-to's, and who will be coming to Champaign in June to do a 2-day workshop (free) -- and we've still got a few spots left if anybody's interested. Champaign is in central Illinois ...https://www.eventbrite.com/e/geogebra-workshop-at-parkland-college-tickets-45538951229