Friday 10 April 2015

MFM2P - Day 41 (Trig)

Today's warm-up got complaints because it was too easy. I will switch it out in favour of something more challenging next time.

Today was all about trig. I gave them a few minutes to work on some examples where they had to solve for an angle. We consolidated with this one, where they were given the lengths of all three sides so could choose which ratio to use. When I wrote the first student's solution on the board, some thought they had done it incorrectly until they saw the answer. It was good for them to see multiple ways of solving this question.

I let them work for about 10 more minutes on finding angles before we stopped to look at how to solve for a side. These are from their exercise books:

They seemed to understand quite well. When we got to the second example they tried multiplying the numbers together and we got about 5.4. I asked if that looked right and they said no! I loved seeing them realize that the hypotenuse had to be longer than 8 cm so we had clearly done something incorrectly. Upon their suggestion, we tried dividing and they thought the new result was much more reasonable. I have struggled in past years with this process - so many of my students have difficulty with algebra and get lost when you show how to solve these equations in a more formal, algebraic way. I have decided that I am okay with them reasoning through, possibly getting it wrong and fixing it.

They worked for the rest of the class on this handout while I circulated. Stickers were good motivators today and I was very impressed with the work I saw.

1 comment:

  1. Thanks for all your great posts, Mary. I've been reading your blog this semester and following along behind your cycling. You are such a great resource!

    Last time I did trig with my 2Ps I had a brainwave about how to explain the rearranging/dividing thing. I went back to a simpler fraction like 3 = 12/x and we talked about how that means "12 is cut into some number of pieces that have a size of 3, so how many pieces was it cut into?" They all got that 12 was cut into 4 and they were able to understand that they had divided to get there. It was then easy to extend that back to "8 is cut into y-number of pieces that are 0.7431 big..."

    Thanks again for sharing your 2P days with us!