Reflection: Connection to Prior Knowledge Discovering Trig Identities (Day 2 of 4) - Section 2: Investigation


When looking over my students’ work, I was intrigued by the various answers being given for question 4. Technically, students should already have prior knowledge of how changing the ‘a’ value would affect the graph. We just got done studying the key aspects of trigonometric functions and how parameter changes affect the graphs in the last unit. This question showed me that my student either did not retain much of that knowledge or were not connecting to their prior knowledge for this question.

Here is a variety of levels of answers for question 4 that I observed:

Good use of mathematical vocabulary

Could be better with more detail

True (but not the answer I expected yet)


I wondered if the difficulty with this question stemmed a bit from the language of the question. During class, I had many students ask me what the worksheet meant by the word parameter. I thought I had used that term when we studied trigonometric functions in the last unit (or at least in the whole first semester when we studied a variety of other functions!) When I followed up with the prompting question of “As a changes how does the graph change?” many more of my students were able to understand the question. Apparently, I need to work more on using the prompting question “As the PARAMETER a changes, how does the graph change?” I think that would help my students in the future with this type of question.

Even once students understood the question, I still got a few wrong answers. I think these two examples would be great for a Favorite No activity. They would provide a great opportunity to help students be more precise with their mathematical language (Mathematical Practice 6).

Good Opportunity for a Favorite No

Another Favorite No



  Connection to Prior Knowledge: Student Work - Question 4
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Discovering Trig Identities (Day 2 of 4)

Unit 9: Trigonometric Equations
Lesson 2 of 16

Objective: SWBAT visualize and interpret the trigonometric identities with a focus today on negative angle identities.

Big Idea: Students use TI-Nspire calculators to develop their own understandings of what trigonometric identities are and why they work.

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3 teachers like this lesson
Math, Precalculus and Calculus, Trigonometry, Trigonometric identities, ti, 12th Grade
  55 minutes
student on calc day 2
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