standard_description: 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. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.
problem_activity: Stage 5: Fractions of Angles
Required Preparation
Materials to Gather
Protractors
Materials to Copy
Blackline Masters
Target Measurement Stage 5 Recording Sheet
Target Measurement Stage 5 Spinner

Narrative
Students spin a spinner to get a denominator for their target fraction. They choose a fraction less than one with that denominator and estimate an angle measurement that is the target fraction amount of 180. (For example, if a student gives a target fraction of ⅚, they estimate when they think the angle is 150 degrees.) Then students use a protractor to find the exact measurement.


aligns: no