It was kind of an unusual reorg. Desmos used to have a team making curriculum and classroom activities in addition to the graphing calculator. Most of these were essentially just graphs made in the graphing calculator, taking advantage of features like image embedding and draggable points, wrapped in a little scripting language and slideshow UI. When education people talk about "manipulatives", it's usually these kinds of simpler activities and not the whole graphing calculator.

That team got acquired by Amplify, and eventually the "Desmos Classroom" tool used to make the activities got acquired by Amplify too, leaving Desmos with just the more consumer-focused graphing calculator stuff. Amplify also acquired this other "Polypad" product and kind of merged the two together into what's now called "Amplify Classroom".

I think Amplify is still selling/distributing a lot of the activities that were originally made by the Desmos people.