MnSTEP Teaching Activity Collection > MnSTEP Activities > Newton's First Law (Inertia)

# Newton's First Law (Inertia)

#### Summary

In this classroom activity, students will investigate Newton's first law by observing inertia in a variety of experiments. Students will hypothesize on possible outcomes and write observations of what has happened. Students will create a statement that best describes Newton's first law based on experiments.

## Learning Goals

Students will be able to develop an understanding of Newton's first law by creating a definition.

Students will be able to apply Newton's first law to real life situations.

Key Concepts:
Newton's first law
Inertia

Key Vocabulary:
-Inertia

-Forces

-Acceleration

## Context for Use

This activity would be taught to 6th graders, small grouping for experiments and whole group to discuss findings. This would be a multi-day activity. I would use 3 to 5 days to teach this concept. Ideally I would dedicate a minimum of 30 minutes each day for the given experiments. This activity has a variety of needed items, which are easy to find.

Subject: Physics:Classical Mechanics:Newton's First Law
Resource Type: Activities:Classroom Activity
Grade Level: Intermediate (3-5), Middle (6-8)

## Description and Teaching Materials

Materials:
Demonstration:
-7 2x4 square blocks
-Hammer

Penny drop: (for each student)
-Index card
-Penny
-Clear cup

Washer slide: (for each student)
-5 small washers (pennies also work)

Table cloth pull: (groups of 3-5)
-Cloth sized about 4ft x 4ft
-2-3 medium containers with a little weight in it

On day one, have students write observations of the stack of 7 blocks on the edge of the table. Students will generally write what it looks like, color, etc. Guide students to what the blocks are doing. After they have written and/or drawn what the blocks are doing, ask students to predict what will happen to the blocks if the hammer hits the bottom block. Students should write what they think will happen. This would be a good time for a think, pair, share.
Before you do the demo have the students move at least 20 ft away from the blocks. Hit the bottom block quickly (practice before doing this in front of class). It should fly out and the other six blocks will drop down and stay in its stack. As a group write down observations of what had happened. At this point I would introduce the word force and that we will investigate what Newton's first law is through experiments.

After the demo and the group observations, give students a penny, index card, and a cup. They will get to experiment with inertia by placing the card on top of the cup and placing the penny on index card. Have students flick the card from the cup while holding the cup in place. They should write down observations of what happens to the index card and penny. This should be performed several times, encourage students to try different ways of flicking the index card (experiment for about 5-10 minutes). Have students write down observations of what happened: how many times the penny drops into the cup? Did how you flicked the card change what happened? Etc... Then students should write everything they notice about the penny. Give about 5-10 minutes. Ask students what are the qualities of the penny? After observing the penny at rest, ask if the penny moved on its own while observing? At this point students have an idea of how movement works. I would introduce the word inertia. Then as a class, create a rough draft of what Newton's first law is from the observations of the experiments. Our definition of Newton's first law will continue to develop through experiments done in the following days. It should evolve enough to look similar to the actual definition.
The next day, have students test how washers react when stacked. Then have the students take one washer and slide at the base of the stack. The bottom washer in the stack will fly out from the force of the sliding washer. Students should notice that the other three washers do not move from the stack. They will drop a bit but stay intact like the blocks. During this time the students should be using the class created definition of Newton's first law. They should also start using the words force and inertia for describing what is happening to the stack of washers. Have the class regroup and discuss what had happened and if we could add to our definition of Newton's first law.

At this point we have a fairly good definition of Newton's first law. This is a fun wow factor for the students to do this next experiment. This activity should be done in groups of 3-4 students. I would ask how many students have seen a tablecloth pulled from underneath a beautifully arranged setting. Ask the students how might someone do this using what we know about force. In each group they should have a cloth and three containers with a little weight. Have the students place the cloth on the table/desk with a corner hanging off. Put two of the containers on top of the cloth and put the last one on top like a pyramid. Students should take turns trying to pull the cloth from under the containers without knocking the containers over. This will be hard for some of the students. It takes the right amount of force and the direction in which they pull. Students should get about 15-20 minutes to do this activity. Once they have tried this several times have them write down what they have found out. After about 5-10 minutes to write down observations bring the class back to discuss the findings.

I would further the understanding of Newton's first law by using Force & Motion: Stop Faking It! by William C. Robertson. It has an activity testing inertia in other ways.

Source References:
Robertson, William. Force & Motion: Stop Faking It!. Arlington: NSTA, 2002.

Yamasaki, Isao. Scientist Badge training. Science Museum of MN pre-test, observation sheets for demo (Microsoft Word 30kB Aug19 08)

## Teaching Notes and Tips

I have done parts of this lesson for large groups of boy scouts but not in the classroom. I would use caution when doing the demo. Make sure students are at their seats and not sitting on the floor. The blocks go relatively far on smooth surfaces. The penny drop, you should keep in mind that if the students don't hold the cup it will tip over. I would also suggest designating roles for students in the multi-partner activities, such as builder, puller, and recorder. These roles should rotate as the students take turns trying.

## Assessment

In the groups they are in for the tablecloth pull. I would have the group create a poster that defined force, inertia, and Newton's first law by using the tablecloth experiment. They should be able to identify the force is created by the pull of the cloth and the inertia is when something tries to keep doing what it was doing. The containers not flying off the table would show that. This should include a diagram of the experiment and arrows that show the forces at work.

## Standards

The student will describe motion of objects.
6.II.D.3
The student will recognize that unbalanced forces acting on an object change the object's speed and/or direction.
The student will understand that science is a way of knowing about the world that is characterized by empirical criteria, logical argument and skeptical review.
6.I.A.4
The student will define scientific facts, laws and theories.