Thread:Feedback from trial session (1)

Hi Declan,

I had 3 high school students at our skull measuring session yesterday. We encountered a few issues and the students struggled a bit with the conversion, but by the end we had a established a routine which we think worked well. Here is some feedback from our experience:


 * 1) The students had looked over the written procedures beforehand, but as we discussed the conversion calculations, it was clear they didn't understand it. So I rearranged the calculation to look like a more typical conversion calculation:
 * $$length\ (cm) = length\ (photo\ units) * \frac{ruler\ length\ (cm)}{ruler\ length\ (photo\ unit)}$$
 * I decided to use "photo units" as the units, as we were measuring using computer drawing tools and it was unclear how the supposed inch measurements worked. We had two different laptops and the measurements (listed as inches) came out different, more than would be expected through measurement error.
 * 1) After going over this conversion formula, the students still didn't seem to get it, so I compared the conversion to converting inches to cm using the same set up:
 * $$length\ (cm) = length\ (in) * \frac{1\ (cm)}{2.54\ (in)}$$
 * One girl still wasn't sure, but as we progressed I think she became more confident in her understanding.
 * 1) The students did not have open office on their laptops, I figured this would be the case and wrongly assumed that powerpoint would give the length of the line. We looked and looked and couldn't find it. But even before we decided the actual length was not available, only the x and y displacement, the kids had figured out they could use the pythagorean theorem with the x and y to get the hypoteneuse of the right triangle. Good solutions on their part.
 * 2) The plan was to create a google spreadsheet with the data from the measurements. We started out with 4 variables: ID, state, width and length. As you can imagine from what I've said, we ended up needing many more variables, x and y compenents for each skull measurement, along with x and y components for each ruler, and then the calculations for the hypoteneuse for each and then the conversion to length cm and width cm. I had to help the students with this part as they were a bit overwhelmed with how to set it up.
 * 3) We only had time to complete measurements on a few skulls. We meet again in two weeks and if there's interest, we'll continue the task....two students were absent yesterday, and it'll be useful to have the kids who were present explain how to do the measurements to the two who were absent.
 * 4) We measured skull 209 twice, as your measured length was provided in the instructions: 18.22 cm. Our first measurement was 19.85. Our second measurement was 17.94...which seemed more reasonable. Offers a good opportunity to talk about measurement error. I wonder if different measurement procedures generate more error than others.
 * 5) I wondered if we would get better measurements if we had a larger photo image. One of the students started to make it bigger, but when I commented that she needed to be careful to keep the same aspect ratio, she decided to use the smaller image.

Just some thoughts for consideration. Thanks for the opportunity to do some biology-related measuring. If we get measurements on a few more skulls, we'll try out some analysis procedures.

Alison p.s. I added our measurement results for skulls 209, 201, and 202 to the discussion tabs on the relevant pages.