Materials: small bouncy balls, wooden cubes, triangular prism blocks, books, ramps, and science journals
The students will work in groups of three today. They will build a small incline and roll various objects down the incline. They will compare and contrast the easiness that each item rolled down the incline and record their ideas in their notebooks. They will finish the lesson by writing their ideas of why cars have round wheels instead of square wheels.
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 affected 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 also important that students learn that pushes and pulls can have different strengths and directions, and can change the speed or direction of its motion to start or sot it. 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 will gather on the carpet and face the Smart board. I show them the following video.
"I am going to play a video for you. I want you to watch it and then we will quickly talk about it."
I then play the video.
"What was different about that truck compared to cars and trucks that we are use to? Do you think we should make cars and trucks with those kind of wheels? Is there a reason that cars and trucks have round wheels rather than square ones? What about triangular wheels?"
"Today you are going to experiment with different shapes and decide what shape are best for cars."
"I want you to open up your science notebook to the next available page. Please put today's date and the focus (moving shapes) in the upper corner of the page. I am going to hand each of you a piece of paper. It has a question on it and I want you to glue it in your notebook. The question asks; Are certain types of objects easier to move around? This will be your focus during your investigation."
I will have those question typed up and ready to be glued into their notebook.
"I am going to put you in teams of three. You will each get a ball, a cube, a triangular prism, and a board to make a ramp out of. I want you to build a ramp and test how easily each shape can proceed down the ramp."
I am purposefully not telling them how high to make the ramp. I want to see if students test different heights on their own. Inevitably students create a ramp with almost a straight vertical drop and claim that the square cube can roll just as fast as the ball. As students are working, I look for "unfair" tests. I note what students are doing and use their ideas later in the lesson. Along with taking the notes, I will talk with each group (who are conducting the unfair tests) about the concept of fair tests and comparing that to the test they are currently doing. The concept of "fair and unfair" tests is explained in the Explain section of this lesson.
I have included a clip of a conversation (Applying Force to Move Triangular Prism) that I had with a student. I wanted her to explain/identify that she had to apply an extra force to make her cube slide.
"You can test each item as many times as you want. You should record your findings in your notebook. As you are recording, I want you to compare and contrast the different objects that you tried on a scale of easily moves to not as easily to move."
I have included a clip that captures students explaining why a ball rolls more easily than the prism.
I ask the students to clean up and meet on the carpet and to bring a chair and their science notebook.
"Please clean up all of your stuff, bring a chair and your notebook, and create a circle for our science circle discussion."
"Today, you had the opportunity to test a few items and to find out which objects moved more easily down the ramp. I would like you to stand up and find a seat next to someone that you didn't work with during the investigation. I would like you to take a few minutes to share with each other what you found out. Once you are all done sharing, I will ask you to tell me what the other person (talking to you) learned."
I do this because I want them to continue to practice using their notebooks to inform or aid in a conversation. I also ask kids to report out on what the other person shared, to reinforce the concept that they need to be attentive listeners and learn from each other.
"Now I would like people to share what you learned with the whole group. Would anyone like to add anything to the discussion and/or about the focus question?"
After the discussion, I want to turn the attention to the idea of "Fair Tests." Again, I will use examples from students work during the investigation time or I will create a scenario where it is an obvious unfair test (i.e. roll the ball on a slight incline and the cube on an incline that is so steep that it just slides. Either way I have the example modeled and then have the following conversation:
"Why is this considered an unfair test? What would make it a fair test?"
"Whenever you are testing items, you must test each item the exact same way. Each time you change something or add/take away something, you are changing a variable. Scientist always make sure that they conduct fair tests and only change 1 variable at a time."
To reinforce this I build a small ramp and test each item. I then raise the height of the ramp and explain that I am now changing a variable from the first time I tested. I feel this visual model will help reinforce the ideas of fair tests and variables.
"I want to watch the video that we saw at the beginning of the lesson again. After it is done, I want you to complete the following task. You are in charge of building your own truck. I want you to draw a picture of it and show me what type of tires would allow the truck to go the fastest. Would you want square, triangular, or round tires? Make sure to label your trucks tires and explain why you made the choice that you did."
I have the students work by themselves on this task. I want to see how well each student connects to the ideas of today's activity. If a student was to just draw circles and explain that their car has 4 circles so that is what they drew, I would ask them to defend their answer based on their testing. "Based on your testing, why does your car have four round tires?
I look at the students answers to the truck tire sheet. I am hoping to see that they chose the round tires over the other two shapes, realizing that round tires would be the same as the ball and would roll the easiest.
I am looking for students to connect round balls to round tires and that their are no edges and therefore move quicker and more easily.