We can clearly see two lines. One is blue and the other one is black. We can change the position of these two lines with free points A, B, C and D. We can see that the two lines are intersecting and making two adjacent angles α and β. Let us move the free points A, B, C and D and observe how these two angles get changed.

Questions to think about
1. Move the points A, B, C and D and find α+β, what do we observe?
2. Is it possible to get α+β ≠180˚?