We hit the toilet paper estimations today, some with video answers. This prompted one student to ask how [Mr. Stadel] had time to do this. I'm sure many of us have asked the same question!
The plan for today was to go outside to find the height of inaccessible objects using similar triangles. I thought we should go over how to solve for a missing side using similar triangles first, not least of which because I had a new student join my class at the beginning of cycle 2 who had therefore not seen similar triangles. So I handed out printouts of the great picture from the Estimation 180 site of Andrew and the lamppost and their shadows.
I wanted them to measure the two shadows and Andrew and use similar triangles to calculate the height of the lamppost on paper (I know they could just measure it, but they needed to practice using similar triangles). Then we would use Andrew's actual height to get the actual height of the lamppost. This did not go well. Picking up a ruler and measuring seemed a difficult task for some groups. Yes, they were doing this in groups - should have been straightforward, no? Apparently not. A couple of groups did find a scale factor around 3 but that is as far as they got. The other groups, well, they were still (or not) measuring. Sigh. This probably should have been an indication that taking these children outside to measure longer distances might not be a good idea...
However, I had said we would go outside so outside we went. The sun was not cooperating so we took the mirrors with us, along with measuring tapes and metre sticks. It was cold outside, but I had asked them to get their jackets. Getting them to do anything was painful. They really just wanted to break through the ice that had formed on puddles - as my 4-year old loves to do. Sigh. I got each group (I think) to get one set of measurements for the lamppost outside and then we went back in and I told them to figure out the height of the clock which is suspended from the ceiling. Again, a lot of non-activity followed. So I had to get them to stand up and walk over the to the clock and put their mirror on the ground and back up and ... Argh!
I think I tried to cram too much into today. I should have skipped the picture and gone straight to the two examples that were part of the handout for the actual activity. We should have practiced using the mirrors in class before venturing out. The funny thing is that I have done this activity many times before with kids who are less cooperative than the fantastic class I have this year, and it has gone really well. I think we will re-do it later in the semester when it warms up and add some clinometer action to the mix. In the meantime, I will pick up the pieces tomorrow.
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