Plotting one point over another and getting that point to appear filled in

Suppose a student plots a set of points with hollow circles and then I want one of those circles (-1,-16) to become filled in when the student plots that point again. Is there anyway to do that?

Its in slide #2 in the activity linked below, but the points need to be plotted on the slide #1 for there to be an issue.

Where are they plotting it “again”?

Also, I think you meant “ordered pair” not “coordinate” in your Slide 2 question. That or plural “coordinates”.

Yes, I mean an ordered pair. They plot points on a table on slide one (with hollow circles) on slide #1 and the points carry over to slide #2, but on slide #2 after they draw on the sketch, a box appear that I want them to enter the ordered pair (-1,-16), but since this point is already plotted nothing changes on the graph.

I changed the code a bit so it would plot if the point is (-1,-15) because nothing is plotted there, but not (-1,-16) because the point is already plotted from the previous slide.

You could use a button for entering the ordered pairs. Use capture to get the x and y coordinates, and set numberLists, X and Y, in the graph on Slide #1 to the histories for the captures. Plot (X,Y) and set to closed dots.

Thanks so much. I actually decided to plot a circle which is only a little bigger than a point to get the effect I want, but your advice has helped me make some really wonderful activities.