If a washer was suspended from a kite string, acting as a pendulum, and swung at a fixed point, what would happen if the string was cut at the highest point in the washer's elevation? Mary Bell explored this question with a group of her colleagues, and then later with a group of 5th and 6th graders. The Pendulum Question was a very interesting article, particularly after we had unknowingly simulated the experiment in class. During our class discussion, I originally thought that, "If the pendulum were to be released at the highest point in its arced path [...] it would rise slightly higher in the arc due to centripetal force and then fall quickly downward in a bell curve form." I thought it would be similar to a child jumping off of a swing. I also wrote that the motion of the washer after cut would be dependent on the weight of the pendulum in comparison to the string, how and where the string was cut, and how accurately it was released.
We discussed as a group, and most of our thoughts were fairly similar. The biggest difference was whether or not the washer would arc upwards or not... like keys on a lanyard. The amazing thing was that in Mary Bell's article, the students made very similar predictions. I really thought it was amazing that kids in such young grades were thinking on the same lines as a college class, and according to Mary Bell, along the same lines as experts. Bell stated that it took three weeks for them to discuss all of the possible options. In the classroom, it took the students only a fraction of that time. In fact, the correct answer was unearthed in Bell's classroom in barely ten minutes of discussion! The most important part in my opinion was the students working together to not only prove but disprove several of the solutions to the question.
The "it depends" factor was very prominent in their discussion. The students were looking at the question from all angles like how fast was the pendulum was swinging, how heavy the washer was, exactly how it was released, and how high the swing was. The students struggled to articulate their ideas because of a lack of vocabulary, but were still able to work through it together. They neglected to use the real world examples as Bell had hoped, but she was able to bring it back in to conversation. My example of jumping off of a swing was brought up, but then I realized, just as the students had to, that the way a person would release from a swing and a washer would release from a string was completely different. A person is not attached to a swing unlike the washer and string, therefore it could not be compared. Something like the keys on a lanyard example would be much more accurate, and once I considered that example I had to reconsider my prediction! This taught me how important it is to consider real-life examples that are as similar to the experiment as possible. I also liked looking back in my notes (and Bell's students predictions) and seeing the changes of opinion after discussion. I thought this was really a fascinating experiment as far as the pendulum question and the way students interpreted it.
