Angles formed when a transversal intersects parallel lines

Estimated Time
90 minutes

Prerequisites/Instructions, prior preparations, if any
Laptop
 * 1) The students should have prior knowledge of parallel lines, transversal, angles and types of angles formed when a pair of parallel lines are intersected by a transversal.
 * 2) They should know what the terms interior, exterior, adjacent, alternate, consecutive, congruent, linear and corresponding mean.
 * 3) Students should know the definition of complementary angles, supplementary angles, and congruent angles.
 * Multimedia resources :
 * Website interactives/ links/ / Geogebra Applets :



Materials/ Resources needed
Laptop, geogebra file, projector and pointer.

Process (How to do the activity)
Linear pair of angles - adjacent and supplementary
 * 1) Reiterate that when a transversal intersects parallel lines, several pairs of congruent and supplementary angles are formed.
 * 2) Have students draw two parallel lines and a third line(transversal) intersecting those two lines on their own paper. Direct them to think about any angle relationships they see. Have them discuss their conjectures with a partner.
 * 3) The teacher can next project the GeoGebra worksheet and discuss about types of angles and their relationships with the class.
 * 4) Finally the teacher and students can summarize together the angle relationships.

Vertical angles - congruent

Corresponding angles -congruent

Alternate interior angles - congruent

Same side interior angles - supplementary

Alternate exterior angles - congruent

Same side exterior angles - supplementary

Developmental Questions (What discussion questions)  :
 * 1) How many pairs of corresponding angles are there ?
 * 2) What is true about corresponding angles formed when parallel lines are cut by a transversal?
 * 3) Compare different pairs of alternate interior angles. What do you notice?
 * 4) <EGD and <AHF are alternate exterior angles. What is another pair of alternate exterior angles?
 * 5) Compare different pairs of same-side interior angles. What do you notice?
 * 6) Compare different pairs of same-side exterior angles. What do you notice?

Evaluation at the end of the activity

 * 1) What are the characteristics of linear angles (adjacent and supplementary) ?
 * 2) What do you observe about the angle measures of the linear angles?
 * Question Corner :
 * 1) What do adjacent, alternate, linear , corresponding and consecutive mean individually
 * 2) What are complementary angles?
 * 3) What are supplementary angles ?
 * 4) What does it mean if two angles are congruent?
 * 5) What is the complement of 65 degrees
 * 6) What is the supplement of 70 degrees?
 * 7) Compare angle relationships formed by parallel lines vs. angle relationships formed by non-parallel lines.