## Reflection: High Expectations Period and Amplitude - Section 2: Reviewing the graphs of sine and cosine

I have found that expectations need to be clear when teaching students to graph.  I do not expect perfect graphs with every point in place as this is unnecessary, but I do have certain expectations.  When left to their own devises, students will often draw a sloppy graph with no units labeled.  In fact, even with clear expectations, students will sometimes turn in inadequate graphs.  This has been a challenge for some of my students this year.

Here are my expectations. There are always key points associated with a function that much be shown.  I insist on tick marks with units labeled if a scale other than one is used.  I want to graph to extent across their coordinate plane.   I also encourage them to use graph paper as this will naturally improve the quality of their graphs as the proportions are already set.

For the parent Graphs of Sine and Cosine, I use the interval of 0 ± π as my point indicators.  For sine functions, 0 ± π are the x-intercepts.  For cosine, 0 ± π are the local maximum and minimum.  By plotting these points, my student’s graphs are more proportional and this really helped when we started changing the period or shifting the graph horizontally.

High Expectations: Improving Graphs of Sine and Cosine

# Period and Amplitude

Unit 9: Trigonometric Functions
Lesson 9 of 19

## Big Idea: What makes the graph of a trig function unique? Find out in this lesson.

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Subject(s):
Math, Trigonometry, Trigonometric functions, amplitude, period shifts, periodic functions, period, Algebra 2, master teacher project, sine graph, cosine graph
59 minutes

### Amelia Jamison

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