[b]Background[/b][br]The red and blue horizontal lines on the [i]GeoGebra [/i]work-space are parallel – they will never intersect (cross each other).[br][br]The straight green line, as you can see, intersects the both the red and blue parallel lines.[br][br]Observe that whenever two lines cross each other, there are four angles formed (see the diagram below with the angles labeled).[br][br]Notice that Angle A and Angle B on the [i]GeoGebra [/i]page are both in the same relative location. They are in the Angle 1 location.[br][br][b]Step 1.  Collect Data[/b][br]Use the MOVE tool [icon]/images/ggb/toolbar/mode_move.png[/icon]to move the [b]Drag Point[/b] to Point 1.  Make a copy of the Data Table below on paper. Fill in the size columns in the Data Table for Point 1.[br][br][u]Point         Size of Angle A           Size of Angle B [/u][br]1 [br]2 [br]3 [br]4 [br][br][b]Step 2.  Collect More Data[/b][br]Now complete the table for Points 2 through 4.[br][br][b]Step 3. Look for a Pattern[/b][br]What do you notice about Angles A and B as you change the green intersecting line?[br]What do you think happens with the other three angles that are not labeled on the [i]GeoGebra [/i][br]page?