The Law of Classroom Inertia

In 2 weeks, my school year will be half over. Since we are on the block, I will have a whole new group of students and will be starting my courses fresh.  As I think back on some of my big ideas from the summer that I failed to follow through with, I think about Newton’s First Law of Motion.  

Newton’s First Law of Motion states that

Every object will remain at rest or in uniform motion in a straight line unless compelled to change that state by forces impressed on it.

This law has also been paraphrased as

An object at rest tends to stay at rest and an object in motion tends to stay in motion.

I prefer to state it this way in my physics course

An object’s motion will only change if acted on by an unbalanced force.

What does this mean in a practical sense? If you are standing at rest, you have forces acting on you that are balanced, or cancel each other out.  There is gravity pulling you down, and the ground pushing you up.  The forces are equal in size and balance each other out. This means that you stay at rest with unchanging motion. If I were to give you a push, though, you would move and no longer be at rest.  You would be put into motion by the unbalanced for I applied to you. Another way of saying unbalanced force is a net force. You have a net force (because of me) and your motion changes.

Depending on your mass, it may require a larger amount of force to put you into observable motion. The amount of mass you have determines your inertia. An object’s inertia is a measure of how easy it is to change that object’s motion.  The more mass the more inertia.  The more inertia, the more difficult it is to change that object’s motion.

Once in motion, an unbalanced force is required to change that object’s motion in terms of direction or how fast it is moving. On Earth, we are used to seeing just about everything that we put into motion coming to rest unless we keep pushing it. That seems to defy the 1st law of motion. We applied a net force, why doesn’t it keep moving. There is some force of resistance to just about everything we push of pull. If you push a desk with a force and let it go, it may only slide a few inches before coming to rest.  Once you start pushing the desk, friction with the floor applies a force that directly opposes your push.  If you stop pushing, friction keeps pushing until that desk is brought to rest.

The more inertia something has, the more force it takes to start it in motion.  The more inertia something has, the more force it takes to stop its motion.

One of the new things I wanted to implement this year was more student reflections.  Specifically, I wanted students to reflect on the Instant Challenges we do once a week to increase their ability to compose quality reflections in all areas of the course (and beyond). Instant Challenges are something my co-teacher Andelee Espinosa brought to our classroom last year. They are taken from Destination Imagination. They are quick 5-7 minute STEM design challenges that force students to collaborate and think about materials differently.  My idea for this year was to have students reflect on the challenge from a habits of mind perspective. Questions would ask students to reflect on ability to collaborate, think creatively, build on previous successes, learn from past failures, contribute to the group, and manage time. I waited too long to to have my students start reflecting on their instant challenges. It became something that I never incorporated into my course.  It couldn’t fight the inertia of my course that was in motion.

You may not think about it but a classroom has mass, it has inertia. As a course progresses, that mass is not constant. As time passes, the classroom gains mass.  It gains inertia. Every practice we set into motion accumulates mass over time. It accumulates inertia. Practices that we set into motion early, tend to stay in motion. As time passes, these practices can seem to have a motion of their own as they travel a straight line path. If we want to change their motion early in the year, it seems to take a simply push to change and adjust that motion. The longer the practices are in place, the more force it takes to change them. It takes more force because of their inertia.

Think about the practices that you find easiest to put into practice. Are they the new ideas that are starting from rest or the ones that have been in motion for years?

Too often, inertia has been called “laziness”. Think about it more as the ability to change. As we try to change our practice, we should expect resistance. Resistance not simply from systems and stakeholders, but from learners as well. Think about the inertia some of the practices a student has been asked to perform over a lifetime of schooling. Think about the classroom practices they have encountered. The habits of mind they have found work for them to be successful in school have an inertia. No wonder it is so hard for them to change to a new paradigm when given that opportunity.

Think about your own resistance to change a practice. How many year have you had a particular practice in motion? How much inertia does that practice have? How difficult will it be to change?  

I plan to bring those reflections to my classroom next term.  The first day of next term, we will do an instant challenge. We will reflect on the instant challenge. This practice will gain mass over time. It will have enough inertia to overcome the resistance to change. At least, until we find a reason to change it.  More on that when we discuss Newton’s 2nd Law of Motion...