Given 4 points, A,B,C,D, we can form 6 pairs of points.[br]Each pair of points gives one line and one mid-point. [br]This figure shows the 6 mid-points in orange. [br][br]How would you arrange the 4 points (A to D), so that the 6 mid-points all lie on one circle? Try to find a more general condition.[br]What do you notice when trying to do so or explain your findings?[br][br](This is an extended version of [url=https://www.geogebra.org/m/aqpw7rnx]another activity[/url] with additional objects here to facilitate investigation. You may also check the video below for sharing of my thoughts on this problem.)[br]