Transversal EF intersects lines AB, IK and CD. Lines AB and IK are parallel, while CD is not parallel to either AB or IK.
You can change aspects of the worksheet by moving the blue points. As you do so, observe what happens to the angle measures. Look for relationships between pairs of angles.

1. Identify a pair of corresponding angles created by the parallel lines AB and IK.
2. Put your mouse on B and change the position of the parallel lines. Pay attention to what happens to the measure of the corresponding angles you identified as the lines move.
3. Find a pair of corresponding angles created by non-parallel lines CD and IK. Is the same thing happening with the measure of the corresponding angles created by parallel and non-parallel lines?
4. Write a conjecture about corresponding angles.
5. Identify a pair of alternate interior angles created by the parallel lines AB and IK.
6. Put your mouse on B and change the position of the parallel lines. Pay attention to what happens to the measure of the alternate interior angles you identified as the lines move.
7. Find a pair of alternate interior angles created by non-parallel lines CD and IK. Is the same thing happening to the measures of the alternate interior angles created by parallel and non-parallel lines?
8. Write a conjecture about alternate interior angles.
9. Identify a pair of alternate exterior angles created by the parallel lines AB and IK.
10. Put your mouse on B and change the position of the parallel lines. Pay attention to what happens to the measure of the alternate exterior angles you identified as the lines move.
11. Find a pair of alternate exterior angles created by non-parallel lines CD and IK. Is the same thing happening with the measure of the alternate exterior angles created by parallel and non-parallel lines?
12. Write a conjecture about alternate exterior angles.
13. Identify a pair of same-side interior angles created by the parallel lines AB and IK.
14. Put your mouse on B and change the position of the parallel lines. Pay attention to what happens to the measure of the same-side interior angles you identified as the lines move.
15. Find a pair of same-side interior angles created by non-parallel lines CD and IK. Is the same thing happening with the measure of the same-side interior angles created by parallel and non-parallel lines?
16. Write a conjecture about same-side interior angles.