Thursday, February 6, 2020

Hands-On Law of Sines and Cosines



I love when teachers freely share ideas and materials online. Although I appreciate the work available in TPT (I use All Things Algebra's Precalculus curriculum and love it), freely shared resources are my favorite.


We were working on the Law of Sines and the Law of Cosines in class today and I was trying to decide what we would do for practice. This class is flipped, so my students had already done the notes.  Even doing a jigsaw with the homework questions seemed kind of dry. Happily, I found this lesson plan on the Utah Education Network.




I didn't do part one of the lesson, which was making a triangle reference model to give a concrete picture of which sides correlate to which angle, although given more time, it may have been wise to do it.



We did part 2 and started part 3 in class. We'll have to finish part 3 next class. Normally, we would have been able to get through part 2 and 3 in one 80 minute period, but we had a quiz and went over it, so the 60ish minutes we had wasn't quite long enough.



I love the hands-on aspect of this lesson--that students are using the Law of Sines and Cosines to find the missing information in the triangle and then actually measuring with rulers and protractors to verify. When we moved onto part 3 I handed out half sheets of tablet paper and several of my students were working hard to make the hardest triangle to solve--as in with the smallest angle possible for one of the vertices. We had just made it to the part of the lesson where students give their constructed triangles with three measurements to other groups to solve when we ran out of time.  Ideally, if students are choosing three different measurements differently for each of their constructed triangles, the students solving them should get an assortment of Law of Sines and Cosines practice.


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