Heat conductivity of materials

The two styrofoam cups are connected by a material to be tested for heat conductivity. The lab included aluminum rods, iron rebar, a wood stick, brass rods, copper cylinders, steel bolts, a length of lead pounded from a fishing line weight, a hunk of basalt, and any other materials we could access. Boiling water goes in the one cup, the other cup is filled with just enough room temperature tap water to cover the material in the bottom. Lynn and Marsela watch for the maximum temperature rise of the tap water.


The hot water melts the glue, so a glue gun is used to repair the styrofoam cups on the fly. This is faster and safer than solvent based glues. Annnie and Clyde work on repairing their cups.



In the 8:00 section I was unable to get a class discussion going. Getting a true class discussion going can be challenging, especially when the topic is terra nova for the students. Asking the students to come up with a chart or graph to use to communicate their results has the students working with science and with charts and graphs. Both areas are unfamiliar.


At 11:00 I knew I had too large a group to get a discussion going, so I simply combined laboratory partner pairs into discussion groups of four to six. I gave each group 15 minutes to come up with some idea of how to present the data. One group was unable to put together any coherent idea, but the other four groups presented a variety of ideas. Three groups utilized variation on a column chart, the fourth group hit upon using an xy scattergraph.

Of interest to me was that no one in either class hit upon the idea of using the change in temperature as the graphed variable. No class over the past three years has thought to use the change in temperature to deal with the conductors having different starting temperatures. The use of delta T is not obvious to the novice. This implies that the concept is more cognitively complex than one might expect.

Those who work in physically sciences might move to the change in temperature almost intuitively, sensing that the change is what we really want to display. Even in the classroom I have to tie my tongue to resist blurting out, "Why not look at the change in temperature from start to maximum?" The key to this discussion however is "no teacher talk time." The students have to wrestle this one down to the ground themselves.

At the very end of class I do wrap up by noting that what they just engaged in, a community discussing results, what those results mean, and how to present those results, are important parts of science.

Alisi presents the ideas of group one.

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