Trigonometry Lesson 7 Episode 1 (Teachers)

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Claire explores whether a point below the midline would be negative or the opposite of a different point they investigated previously. Mary expresses confusion about what exactly they are measuring [2:45], wondering if the height should be negative, as Claire seems to suggest, or positive since they are measuring height above ground. This kind of confusion often occurs when students contextualize mathematics. Note how Mary grounds the task back in the context to make sure she knows whether or not they should use negative heights as they had done in the previous lesson when they were discussing height above or below the midline.

For use in a classroom, pause the video and ask these questions:

1. [Pause the video at 0:49] Try this task before watching Mary and Claire. Suppose April is riding a Ferris wheel with a radius of 36 ft, and whose center is 40 ft high. Draw a diagram to represent this context and show April’s height above the ground at various points on the Ferris wheel.
2. [Pause the video at 3:53] Use the drawing that Claire and Mary made to estimate April’s height at some of the points they have marked in their diagram.

1. [Pause the video at 1:59] Summarize in your own words what Claire and Mary have done and said so far. Talk with a partner to share your ideas. Why did they mark a small section below the circle as 4 ft?
2. [Pause the video at 2:57] Mary expresses some confusion about whether the height at one point along the circle should be negative or positive. Talk with a partner and decide what you think is correct.
3. [Pause the video at 6:31] Claire asks Mary if her process for finding the height at the second stop makes sense. Does it make sense to you? Talk with a partner to revoice Claire’s method. Would you change anything? Is there anything that doesn’t make sense?