Throwing a Ball Off a Merry-Go-Round

The Coriolis Effect causes anything travelling between latitudes to veer off from the straight line of travel; we call this deflection. It is a result of the Earth’s spherical shape and the direction of deflection changes depending on which hemisphere we are in. In the northern hemisphere objects are deflected to the right of the line of travel and in the southern hemisphere they are deflected to the left. This is why cyclones in the northern hemisphere spin counterclockwise and in the southern they spin clockwise. Analogy is incredibly important in education and explicitly so in science. For the Coriolis Effect most earth and environmental science educators are familiar with describing is as like standing in the middle of a merry-go-round and throwing a ball to someone riding at the edge. It is an apt analogy, one I have used many times and even demonstrated on playground equipment.


Illustration of the coriolis force (sphere on rotated plate), animation
Self-made animation for Wikipedia, hereby GFDL Hubi 12:03, 23. Nov 2003

Depending on where the person is standing, their speed will be different, with the person on the outer edge of the merry-go-round travelling faster than the person in the middle. Just as points along the equator are travelling more quickly than those at higher latitudes. So when the person in the middle throws their ball to the person at the edge the ball will have no lateral velocity and it will travel in a straight path. The person on the edge however does have lateral velocity, and from their perspective the ball will curve away; to the person on the edge the path of the ball is deflected.


I bring this all up not because I love the atmosphere and climate science, which I do, but because I am about to experience my own deflection. Physically of course I will be travelling between latitudes as I make my way back up north. However, for the most part my lateral velocity should remain congruent with the Earth’s since I will be driving a moving van. The path my career has been on is about to shift though and it is something I am very excited about but also nervous for. I am excited because of the changes I anticipate, and because of the things I know will stay the same. For instance, my commitment to my students and to developing relationships with them, my commitment to excellence and rigor; I do not think these will be changed and if anything they may be strengthened.  This deflection is going to make me a better educator. I am nervous though because, just like the person on the edge of the merry-go-round trying to follow the path of the ball, I do not really know where this deflection is going to set me down.

moving truck

There is a great deal about the community I recently left that I love, and I want parts of it to remain in my practice. I will even go as far as to recommend these to other teachers as well.  I have been able to incorporate a number of progressive pedagogical practices that I believe have been beneficial to my students, their training as scientists, and progress as students. I do not think these aspects to education are unique to the independent school community, in fact I imagine there are a number of public institutions where similar values and practices are rescripted as well. My deflection worries me not because I believe I will have to leave these practices behind but because I anticipate the challenges inherent with bringing these kinds of constructivist learning practices to more traditional settings.

There are a number of lessons I have learned over the last four years that I hope will assist in maintaining a constructivist education position within a more traditional school setting. I have learned through project based learning the importance of not only authenticity in a student’s work, but also the importance of public critique and revision. STEM education lends itself to this practice easily, think of the steps in the scientific method or the engineering design process. However, we as educators need to allow time for this to happen in the classroom. When I first began to implement this in my own 6th grade class I found that I needed to be sympathetic not only to the needs of my students but to also forgive myself for allowing depth within a subject rather than breadth across a unit. Granted, with a state mandated curriculum I may not believe I have the time to allow for these types of learning experiences. However, Understanding by Design does offer some suggestion in how we may save time to allow for these types of learning experiences. UbD is framework of curriculum design that focuses on teaching and assessing for understanding and learning transfer, and design curriculum “backward” from those ends.

Through Understanding by Design I have learned the importance of beginning with the ends in mind, and backwards planning. I have also learned to be more open in regards to how I treat assessment and to focus on looking for evidence of understanding from students. Do I really need to spend a period on an exam or quiz if students have demonstrated understanding of content already through a lab, group discussion, or even exit tickets? Perhaps if we allow students the opportunity to demonstrate understanding more often and in alternate ways we will find that we do not need to test every bit of content we cover.


A brief aside before I conclude this post. I used the book A Bee in a Cathedral by Joel Levy while writing about the merry-go-round analogy. It is certainly an analogy I have used many times myself, but I did use Joel’s book as a reference. It is an awesome book by the way and explains many (100 to be precise) analogies that science educators often use. I have been utilizing Project Based Learning in my classrooms for the last four years, and recently had formal training in PBL through the Buck Institute for Education’s PBL 101 workshop. Finally, I was introduced to Understanding by Design through some graduate coursework at Loyola Maryland. All of these are great resources and each can lend themselves easily to STEM education. While I am unsure of where, ultimately, I will end up (physically, philosophically, practically) I believe that I will continue to be able to implement many of them as I undergo my personal deflection away from an independent school environment back to a public school one.


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