Materials: Sheets of sand paper, tape, books or blocks, Hot Wheels cars.
The students will work in teams to conduct an experiment that allows them to develop an understanding of friction. The class will start with a gathering as a group and introducing and defining the term friction. Then the students will move into the gym (for the sake of space) and conduct their friction tests. The lesson will conclude with a science circle that allows for a discussion of their findings.
NOTE: Our district in transitioning to the NGSS. Although we are implementing some of the units this year, I am still required to teach units that have now been assigned to other grade levels. This unit is one of those units that has been effected by the shifts in grade levels. I continue to teach this unit because it focuses on the National Science Standard (k-4) B. "As students describe and manipulate objects by pushing or pulling, throwing, dropping, and rolling, they also begin to focus on the the position and movement of objects."
It is important that students understand that "the position and motion of an object can be changed by pushing or pulling. The size of the change is related to the strength of the push or pull." Establishing this knowledge base will prepare them for 3rd grade when the NGSS requires them to apply concepts of force and motion into their learning (3-PS2).
The students all gather on the meeting area and face the easel.
"I want to introduce you to the term friction. Who can tell me what they think friction means? Friction is a force that can slow down objects in motion. Let's write this on a sentence strip and put it on our vocabulary chart."
I find it beneficial to create a vocabulary chart/wall because it allows the students to find all of our unit words in one set spot. Having this allows them to refer to the terms when they are discussing and or writing about their learning.
"Let's think about friction for a minute. If you were to take off your shoes, would you slide around easier on the tile floor or the carpeted floor? I would like you to turn and talk to a partner and discuss what you think."
I give them a few minutes to discuss their ideas.
"What did you decide? Why?"
"You are right. Your socks would slide better on the tile because there is less for your socks to rub against on the tile compared to the carpet. Can anyone give another scenario where something would slide better on one surface compared to another?"
"Today, you are once again going to be scientists and conduct an experiment that will allow you to test the idea of friction. You will work in teams of two, build two different tracks and then race two cars down the tracks. Let's head to the gym for this experiment.
"I am going to choose your teams. Once you have your team, I want you to get the supplies to build your tracks. You will need 4 sections of race track, a piece of sand paper, a piece of construction paper, tape, and 2 blocks that are the same size. You will need to connect the sand paper to the end of one track and the construction paper to the other track (I will had can example to show)."
I am choosing the teams for a specific reason. I am pairing up students that are stronger readers/writers with students that are not. The reason being, that I am allowing them to conduct the experiment on their own. I am around to help groups but won't have to read the experiment steps to each group. This allows students to start working toward conducting experiments independently and is a gradual release of ownership.
"Once you have your tracks built, I want you to take the Race Car Lab Form and fill out the first two parts of the experiment paper. The first question asks you to make a hypothesis about which car will win the race? You should circle the words construction paper or sandpaper. For the 2nd part, you need to tell me why you think so."
"Once you have filled this part out, you need to show me. I will check your hypothesis and reason why, and then I will give you the two cars."
I am intentionally waiting to give them the cars because I want them to fill out the hypothesis and defense of it completely and want them to put thought into it. By holding off on handing out the cars, it eliminates the rush to start racing and allows the students to focus on the components of the experiment.
"Once you have your cars, you will place them at the top (elevated section) of the tracks. You should set the cars so that they are almost ready to fall off. Then you should each lightly tap the cars (at the same time) until they take off. DO NOT PUSH THEM! Then you should watch and see which car get shown the track the quickest. You should repeat the test 5 times."
I circulate as students are testing to make sure that they are conducting "fair tests" with the starts of the cars and also to question them on why the sandpaper track is causing the car to go slower.
"Once you are finished testing, I would like you to work with your partner and complete the rest of the experiment form."
I gather the students back into a circle for science circle and to allow the students to discuss their findings.
"I would like to have discussion about what you found from your testing. I want to know what car won the most in your group and I would like you to explain why you think this happened."
The goal of this discussion is to get the students to identify that the smoother track allowed the car to go faster because of lack of friction. The construction paper track allowed the car to glide across a smoother surface and therefore go farther.
"I would like you to open up your science notebooks and label the corner with today's date and the focus (Friction). I want you to write a letter to me describing what you learned about friction. You can make a diagram about it and /or use words."
I want to see if students identify friction as a force and that it slows an object in motion down.