MFM2P - Day 13

Day 13
We spiralled back today and looked at similar triangles again.  I really wanted them to have a full example for similar triangles in their comp books so I quickly made one up for them to cut and glue.

They did pretty well matching up the angles and I heard some conversations about "scale factor" (yay!).  

Then we continued with trig. They started to have trouble when they realized that they couldn't just do the same thing for every question. They were okay with the difference between finding the length of a side and finding the measure of an angle, but solving for different sides caused problems. Their algebra skills, for the most part, are so weak that they don't have a foundation on which to develop understanding for these questions. They follow when solving an equation like:

and seem to understand why we are multiplying both sides by the denominator. However, when the variable is in the denominator like:

they have no tools to work with. I went over a case with just numbers with them... 14 divided by what gives 7? How could we write this another way? But they had a hard time transferring that to the example shown above. And they just want to memorize what to do if the variable is in the numerator and what to do if the variable is in the denominator. Sigh. I will see if I can figure out a way to better help them tomorrow...