Digital Skills: Developing Online Assessment Skills in Everyday Classroom Activities Western Reserve Public Media

Parallel Lines and a Transversal
Students will learn about the different types of angle relationships formed by parallel lines and a transversal.

I can:
  • I can determine the relationship between angles form from two parallel lines and a transversal.

  • I can solve problems and find all angle measures form from two parallel lines and a transversal.

Tech Skills:
  • Graphing

  • Typing Equations

Materials and Resources:


Student Laptop/Computer


Grade Level:
  • 8th-10th Grade
Subject Area:
  • Math

Activity 1

As a class or with the students in pairs, go to one of the following geogebra sites:

As you or the students check each box of angle pairs and move the points around, take note of what happens to the angle measurements. What conclusions can be drawn from these angle pair measurements? Congruent? Supplementary? Complementary?



Activity 2

Have students go to and follow the directions below. (For information on geogebra tools:



Click on the point tool icon and choose the line tool. Insert 1 line by click on two points.

Click on the line tool icon and select parallel line. Click on the line you just made and insert a parallel line anywhere on the graph.

Click on the point tool icon again (the line tool should already be chosen). Insert your transversal by clicking on points B and C.

Click on the measurement tool icon and choose angle measure. Click on points A, B, and C to find the measure of one angle.

Click on the special objects tool icon and choose the text (abc) tool. Students should use their given angle measure to solve and input the measurement of each angle.



Practice Activity

To show their understanding, have students complete this Desmos Activity.


Write, read, and evaluate expressions in which letters stand for numbers.

Apply the properties of operations to generate equivalent expressions.

Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.


Prove geometric theorems

CCSS.MATH.CONTENT.HSG.CO.C.9Prove theorems about lines and angles. Theorems include: vertical angles are congruent; when a transversal crosses parallel lines, alternate interior angles are congruent and corresponding angles are congruent; points on a perpendicular bisector of a line segment are exactly those equidistant from the segment's endpoints.

Supplementary Resources:

Math Game

Smart Board Resources
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