Forces and Friction

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Objective

SWBAT investigate how friction causes objects to slow down and stop moving.

Big Idea

Pushing, pulling, and moving are great...but how do things stop moving?!?!

Teacher Preparation

In this unit, we have learned all about motion with pushes and pulls. Now, it is time to learn about how things stop moving! This lesson aligns to Essential Standard 1.P.1.1, 'Explain the importance of a push or a pull to changing the motion of an object'. In this lesson, students explore how the force exerted for pushing and pulling objects changes when the surface changes--which changes the friction between the objects. For example, if a smooth plastic tub is pushed along a smooth wooden table, is pushes easily and takes very little force even if it is heavy. This changes if the plastic tub is placed on rough carpet which increases the friction. 

Materials:

*Different surfaces to test (sandpaper, smooth plastic, carpet)

*1 Toy car

*1 wooden block (pretty heavy to provide some friction)

*1 Forces and Friction Recording Sheet per student

*Internet & YouTube access

Warm Up

10 minutes

For students to really understand this lesson, I first show this video called 'In a World with No Friction', which shows the difference between what really happens with friction and what would happen if friction was reduced. This video was produced by students at MIT--I may need to pause it and do a little explaining as we go, but the examples are really good, like a book being slid across a table for kinetic friction. Then, I explicitly teach the definition of friction so that students do not develop misconceptions based on their prior knowledge or the video. I say,

"You just watched several examples of what happens when a force, called 'friction' is reduced. Friction is a force that slows down the movement of an object. Today, we are going to learn about friction and then conduct some investigations together."

I write the definition at the top of a new anchor chart about friction and ask my students to do the same. Then, I tell them that they will take some notes about examples of friction throughout the lesson on their journal page. This helps them to stay focused during the lesson and I have also found it to help them remember information later on, as well as being good practice for note taking later on in their school career. It also serves as a tool for them to return to in later lessons when we talk about friction again--they can reference their notes and recall what they learned about. Recording information supports Science and Engineering Practice 4, Analyzing and Interpreting Data.

 

Investigation

20 minutes

To provide my students with a more detailed understanding about friction before we conduct our own investigations, we watch a quick video about friction. I like to use shorter videos because they show so many different examples in a short time, so the students get a lot of information and many examples that I may not be able to show them in the classroom. Before we watch, I say,

"We are going to continue our list of examples of the force of friction. During the video, though, just watch. Afterwards, I will give you a few minutes to write. Really pay attention because some of the examples go by quickly!"

Obtaining scientific information from media supports Science and Engineering Practice 8 and recording information including observations from media supports Practice 4. I chose to have students watch first and write after this clip because for first graders, sometimes it takes their attention off the video for too long to write down an idea, so I want them to just watch so they get all of the information today.

After the Bill Nye video, I say,

"Now, we are going to investigate together to see what we can learn about friction. So, I have some different surfaces and some objects and we are going to test to see how well the objects move when we push and pull along each one. In your journal on the next page you have the recording sheet for today, so turn to it now".

I provided a recording sheet to help my students organize the data from the investigation. In first grade, I think it is important to really support the investigations so that students can understand the content and not worry so much about where to put the data in their journal, so I try to minimize that stress for them by making the recording sheet easy to understand.

As I lead my students through the investigation, we test 2 objects--a car for kinetic friction, and a block for static friction. I provide lots of different surfaces, such as sand paper, smooth plastic, and wrapping paper, and then I ask my students to think of surfaces in the room we could test. I have the same student test both objects and we talk about trying to apply the same force to both objects to see how they move. Then, after we have tested both, we record the results on the recording sheet. I also record the results on my recording sheet which I project on the Smart Board to help any lower-level writers who may need additional support. Again, recording data and information supports Science and Engineering Practice 4.

After we have tested several surfaces, I say,

"Now, to wrap up today's lesson, we're going to see if you can think about our investigation abstractly - that means, can you figure out what would happen if someone else did the investigation?"


With that, we move to the Wrap Up!

Wrap Up

10 minutes

To wrap up the lesson, I use the Sid the Science Kid friction investigation to see how well my students can apply what we have learned today. I also share this link on my classroom newsletter so students can continue to play the game at home and practice the skill!

After we have played the game together, I invite several students to answer the question"

"Who can explain what friction is now?"

Then I say,

"We have talked a lot about different types of pushes and pulls, including ways to make movements change speed and even stop. Who can share something interesting that you have learned?"

Communicating and sharing ideas supports Science and Engineering Practice 8, Obtaining, Evaluating, and Communicating Information. We are getting ready to move on to unseen forces, the second objective for this standard, and so I do a quick check-in to find out how my students are doing with the topic. If I hear any big misconceptions, we talk about them before we move on to magnets and unseen forces!