We started by discussing how you can tell if two triangles are similar. Despite saying that they didn't want to do any work today, my students managed to come up with equal angles as one possibility quite readily. When prompted about side lengths someone piped up about using a scale factor to find missing side lengths. Okay, we were on track. So I asked them to work on a few practice questions. And they had (for the most part) no idea what to do. So we worked on the first one together, marking up the vertices to know which ones corresponded and finding the scale factor and ...
Then I got them working on the remaining 3 practice questions and some did a great job. Others hadn't been listening and still had no clue. I worked with some of them and got them going and took up the last example for anyone who was still unsure where to start. (In case this is coming across - I'm tired and a little grumpy as I write this having just finished marking 2 sets of calculus tests and having fought with blogger all day to post my last post. I probably shouldn't be blogging right now but I don't want to get behind like I did last week - procrastination is a bad thing!)
Then we started with a little vocabulary... hypotenuse, opposite, adjacent. "What does adjacent mean?" "Next to, beside." "Great!" And then we applied it to a triangle or two:
Students then had to apply this to two right triangles of their own. They drew them on grid paper and had to measure and label the sides and angles then fill in a table.
They did not understand what to do. I went around helping each group, but clearly I need to make this more "user-friendly" for next time. Anyway, they have at least one row filled in (hopefully two) so we will start looking at ratios of sides tomorrow as we actually venture into trigonometry!