You can see these activities at student.desmos.com. There is not much to them. This is just an alternative to the pencil and paper activity you might use to introduce students to the locus definitions of conic sections.
It has the advantage that you can using the teacher menu project good answers and overlays so that you can kind of crowd source the hyperbola (some students might make the right branch and some the left.)
My original graph had students only moving 4 points each and that did not work out great to show the shape of the ellipse. So I upped it to 8 points before creating the hyperbola activity. I might make a parabola one also.
Hyperbola: Code to preview at the student site: 8J8EVZ . . .Link to teacher activity
Ellipse: Code to preview HDDPKM . . .Link to teacher activity
To use the teacher activity you need an account (I just used my Google credentials) and you should experiment with the teacher controls so you know how to make the student responses anonymous and how to overlay them.