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The SimRocket Sessions from the Teacher’s PerspectiveIn Spring 1998 a group of five boys at a local middle school chose to do a science project on model rockets. The seventh graders were approximately 13 years old. For purposes of this document, they will be referred to as Jamie, Chuck, Steven, Kelly and Brent (see picture 1). Their teacher asked me if I would like to volunteer to mentor their project. Science projects were generally mentored by adults from the community. I was introduced to the students as a scientist at the local university who had developed a computer simulation of rocket launches. The students actually already knew me because I had been involved with introducing an unrelated software program to their class earlier in the school year. I met with the students for two sessions, each about 1 ˝ hours long. Fortunately, I had both sessions videotaped. In session A, I introduced the students to the simulation software in a small room adjacent to their classroom. We discussed rockets a bit and spent most of the time firing off several simulated rockets and writing down how high they went. In session B, we fired some more rockets, consolidated all the data collected, computed the effect of different rocket characteristics and successfully predicted how high an eighth rocket that had not yet been fired would go. Between my two meetings with them, the students built and tested model rockets made from large soda bottles and filled with water under pressure. My agenda as a researcher was to see if the students understood or could discover one of the basic principles of experimental science, namely the principle of isolating a single independent variable (such as the shape of the rocket’s nosecone, which could be either pointed or rounded). That is, to see the effect of the nosecone shape on the height of a rocket flight, one should take two rockets that are identical in every characteristic except nosecone shape and compare their flights. Accordingly, I set up the simulation with 8 rockets that differed in terms of their nosecone, fins, texture and engine. The list of rockets was devised so that one could find pairs of rockets that isolated each of the variables. And an 8th rocket differed from the 1st by each of these variables, so that it’s flight height could be predicted by adding the differences computed for each of the variables. The simulation in fact used a computation that did just that: it added up the independent effects of the variables. However, it also included a random “noise” factor so that a given rocket had to be fired several times to find out its average height. As a mentor to the group, I never explicitly stated the principle of isolating variables. In fact we never talked about “variables” or “isolating.” I simply responded to the situation we were in at any given moment and tried to guide the group to solve the problem posed by the simulation by suggesting to the students how I would think about the problem and work on it. Mostly, I made these suggestions by posing questions for the students to think about and discuss. The computer simulation was available at http://GerryStahl.net/previous/simrocket and was accompanied by a web page of instructions. The instructions posed the question: how high will rocket 8 go? It listed the characteristics of each rocket, highlighting the differences between successive rockets visually. The students worked at two computers, firing each rocket several times. For each firing, they noted its highest point and recorded that on a chart I had printed out for them. After rockets 1 through 7 were fired 6 times by each group of students, we compiled all the data on one chart. The log of tape A and the log of tape B show what happened minute by minute during our two sessions. The video clips provide glimpses into the action at various points. Each clip is accompanied by a transcription. An explanation of the transcription conventions is available.
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