Applet contains a modifiable triangle with the [color=#c51414]circumcenter[/color], [color=#0a971e]centroid[/color], and [color=#1551b5]orthocenter[/color] shown.
The slopes of three segments (one connecting the [color=#c51414]circumcenter[/color] to the [color=#1551b5]orthocenter[/color], one connecting the [color=#c51414]circumcenter[/color] to the [color=#0a971e]centroid[/color], and the remaining connecting the [color=#1551b5]orthocenter[/color] to the [color=#0a971e]centroid[/color]) are shown.
From this, students are given leading questions to help them informally discover that these 3 points are always collinear.
