We proved the sine and cosine laws, and the class did ok with explaining the proofs (through a lot of repetition!). And we did something pretty similar with the charts for proving the properties of angles and parallel lines.

At the beginning of the year, I did take them through the proof of the volume and surface area formulas for scale factor, and they did ok with it. I'm not sure many students understood the proof but most gave an honest effort. I didn't take them through the proof for the quadratic equation, because I figured the time would be better spent with them practicing its application.

I don't really like just introducing a formula though, because it seems like it's a magic solution and the relationship is lost. But I also I remember when I was in math class in the academic stream, and proofs were lost on the majority of that class. This is my first year teaching, so I am thinking a lot about things like whether to prove or not.

Thanks for the feedback!