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Introduction to Trig Identities

I don't believe in forcing our students to memorize things. I believe in using the material enough that you gain an understanding and start to recall it. In order to do this you need to practice the material a lot and introduce students to where the material comes from.  I used this approach when having students prepare for trig identities. Instead of lecturing and providing a list of identities to memorize I created a set of 2 worksheets that they did over a few lessons that worked as a group to first graph the parent trig functions, transform those functions, and then in comparing the transformation to the parent function the students were able to find the identities themselves. 

Doing this allowed the students the experience to practice graphing and using the parent functions and reinforced the properties of transformation (especially horizontal shifts) which many students had struggled with when we first introduced them 2 months ago. Doing this by hand and having it checked over by the instructor is really important to me when so much of their homework is done online and doesn't require them to develop these skills or intuitions about these functions.

I saw on the trig test that several students used the same approach as a means to figure out the identities and check their work on the trigonometry test. I was so proud!   That said the first worksheet went really well and the 2nd was a total bomb the first time I taught it. I revised it and used it in supplemental instruction 2 weeks later with great results. I'm really proud of these and thank Ann Lyon for introducing me to the wonders of Patty Paper!

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