## Reflection: Lesson Planning Newton's 1st Law Demonstration - Section 2: Student Demonstration

From the outside looking in Newton's Laws seem simple enough to understand, but with this simplicity comes misconceptions. It is very easy to give students the wrong idea about how our physical universe behaves. The problem with Newton's 1st Law is that because of Earth's gravity students don't think of gravity as a separate force that acts upon objects, rather it is a constant in their lives that they have evolved to exist with.

The version of Newton's 1st law that I teach is:

Objects at rest stay at rest and objects in motion stay in motion, unless acted upon by another force.

I start out by showing the kids a resting object (basketball on a cart) and explain that that object will remain in that location until the end of time. As a class we spend a few seconds staring at the basketball until everyone laughs. Often a student will swat at the object to prove that it will move, but someone inevitably realizes that hitting the object was another force acting upon the object.

The problem for students comes with the second part of Newton's 1st Law. I tell the class that an object in motion (such as a thrown baseball) will remain in motion FOREVER. I let that phase hang in the classroom for several seconds until someone corrects me and tells me that the baseball will fall to the ground after a few seconds. I enthusiastically point out that the baseball fell due to another force acting upon it. As a class we identify what those forces where (gravity, air frictions, etc...). I explain that if wee were to remove the effects of gravity and air resistance and travel to a spot far away in space and threw the baseball again it would travel in a straight line forever.

I teach Newton's 1st Law in two parts. The first part deals with resting objects and is fairly easy for the kids to understand. The difficulty lies with teaching about objects in motion, because it is not what students observe in their everyday life.

Avoid misconceptions
Lesson Planning: Avoid misconceptions

# Newton's 1st Law Demonstration

Unit 6: Forces
Lesson 10 of 12

## Big Idea: Newton's 1st Law is not always intuitive to students. Providing a real world example helps them to understand the physical environment they live in.

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Standards:
50 minutes

### Sean Gillette

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