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Failed Experiment or Successful Learning

October 3, 2012

Over the last two days my colleague and I have combined classes to conduct an experiment to look at linear relationships. This is a key component of the grade 7 curriculum as students examine expressions, variables and how to write mathematical relationships.

The experiment itself seems like an easy one. Students blow air into a balloon attached to a straw and record the distance the balloon travels down a wire. How could the results not be a nice linear relationship. Two breaths must go twice as far as one breath, three breaths even further. Of course this nice mathematical relationship did not happen in the “real-world” where human error is plentiful.  In the end I am not sure there were any relationships between dependent and independent variables for most of the groups.

Our experience in the real world could be summed up as “you can not predict with any degree of certainty” the outcome of how a balloon will go based on the number of breaths placed in it.”  In fact many groups found that the distance decreased as the number of breaths increased. Odd but this is how life goes. The sources of error were plentiful as breaths were inconsistent in size, the wind was blowing, balloons were not attached properly, balloons exploded and wires were placed in a position that could not be considered  level. The results were far from linear.

My first reaction was “What went wrong?” and “What a failure.” I am now more inclined to say what went right … with this learning opportunity. The results are ones we should expect when there is so much experimental error. When we asked the students to identify the possible sources of error they were quick to point out all of the things I had seen and some I had not. This was a great learning experience for them and me.

The question now is what do I do tomorrow? We obviously have an experiment that failed to show the linear relationship which was anticipated. However, I do think this gives the class a chance to talk about  the number of trials, how science really works and how regression (I will not use this term in grade 7) is used to show relationships between variables. We may even see if we can improve upon our results through a more controlled environment.

Overall I am considering the two days a success. Success can not be measured in terms of the primary goal but the other learning that occurred. This once again proves that there is a lesson in everything and emphasizes why teaching is such a great career.

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