Easy, breezy, beautiful!
Since everyone had such a hard time last class, we started by watching this from 0:23 to 0:55 over and over and over. There was productive discussion. It helped. I will start with this and a discussion next time, maybe…I am struggling finding the balance of “helping” that results in productive struggle.
In some classes I also played the video of one of Fawn’s students explaining her thought process from her post on this activity. Most students were confused by this, and focused on her nail polish. I probably will not include this next time.
Since Fawn’s similar triangle lesson was so beautifully written here, I pretty much printed out her blog post and ran the class verbatim. I quickly realized that my students are not as enthusiastic problems solvers as Fawn’s and it’s because I don’t let them struggle enough. I’m working on it. They struggle a little, but at some point I jump in, and then kick myself later. This became evident to me as I compared my students reactions to Fawn’s descriptions. I got more of the “YOU’RE NOT HELPING ME!!” “It’s your job to help, you are not doing your job” types of comments. I stopped the class, we had a good group discussion on how they could be convincing that they found the exact point to hit the ball in order for it to go in the hole. They got back to work. They need more time. Some students figured out what to do right away: Others really were a mess. I am learning a lot, at least. We will continue on Monday. I’m sure it will be a success.
I started off introducing the lesson using Dan Meyer’s idea here. Students had great debates about which triangles are useful in finding the height of the lamppost. Some students came to the board and drew triangles on the house in the background, or other random locations, then I asked, which of these triangles are similar? There was very productive discussions among the students & I just persisted with “explain that” and “how do you know” and “show me on the board.”
The quote of the day was from Barbara:
We then completed some examples in their interactive notebooks:
We measured the classroom using similar triangles together, and then students worked in pairs outside. I would definitely do this again. I think they learned just as much about using measuring tape and converting units as they did about proportions and applications of similar triangles. We also followed this up with discussion on possible sources of error or discrepancy’s and reasonableness.
For some reason on my way to work I remembered Kate Nowak’s Speed Dating activity. It was a nice change, but for some reason I could not get the students to rotate so that each student worked with each other student. I cannot figure out what the heck I did! It usually ended with “OK, pair up with someone you have not yet met with.”
Most students appreciated the change in format.
I gave students patty paper, a ruler and an image with 2 similar figures. They were provided with some guiding questions & their task was to conclude the properties necessary for figures to be similar. Next year I’d like to make this more rigorous by providing students with a collection of pairs of polygons that are similar & pairs that are not and leave off the guiding questions. I think it would be a much richer task. I felt like I was dragging them along instead of letting them explore.
After this activity, I projected a series of images of similar figures and students decided if they were similar or not and explained how they knew.