standard_description: Derive the formula A = 1/2 ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side.
problem_activity: Optional activity
Students measure their proposed 5K courses with their trundle wheels. They compare their measurements with their estimates and make final adjustments to their proposed courses. Then they draw a finalized version of their course on the map (or a second copy of the map) including all the details necessary to organize the race: start and finish locations, walking direction, and number of laps.
Launch
Keep students in the same groups. Provide access to trundle wheels. Tell students to measure their proposed race course twice, record their measurements, and then to come back to the classroom to finish the computations and revisions.
Student Facing
Measure your proposed race course with your trundle wheel at least two times. Decide what distance you will report to the class.
Revise your course, if needed.
Create a visual display that includes:
A map of your final course
The starting and ending locations
The number of laps needed to walk 5 km
Any other information you think would be helpful to the race organizers
Student Response
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Student Facing
Are you ready for more?
The map your teacher gave you didn't include a scale. Create one.
Student Response
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Activity Synthesis
Ask students to display their maps and explain their proposed race courses. Consider doing a gallery walk. Encourage students to discuss any assumptions they made to complete their calculations as well as any revisions they made to their plan after measuring their proposed course.
Representing, Conversing: MLR7 Compare and Connect.
Use this routine to help students consider audience when preparing a visual display of their work. Ask students to consider how to display their proposed race courses so that another student can interpret them. Groups may wish to add notes or details to their drawings to help communicate their thinking. Provide 2–3 minutes of quiet think time for students to read and interpret each other's displays before they discuss any assumptions they made to complete their calculations as well as any revisions they made to their plan after measuring their proposed course.
Design Principle(s): Cultivate conversation; Maximize meta-awareness


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