Predicting the Force
Lesson 6 of 6
Objective: SWBAT predict the effect of a force on an object.
In this lesson, students predict the effect of forces on objects in motion. This has real-world applications, especially for first graders learning to ride bikes and skateboards! Forces that can change the motion of an object can be kinetic (moving) or static (not moving). So for students thinking about riding bikes, for example, a rock in their path would be a static force causing them to crash! During this lesson, students watch examples and make predictions of the effect of forces on the motion of kids on bikes and skateboards. This lesson aligns to Essential Standard 1.P.1.3, 'Predict the effect of a given force on the motion of an object'. Click here to hear an Explanation of Essential Standards and Essential Question. The essential question for this lesson is "How can I predict the effect of forces on objects in motion?"
*Predicting the Force Recording Sheet (1 per student)
To start the lesson, I say to my students,
"Today we are going to answer this question: 'How can I predict the effect of forces on objects in motion?' We have learned a lot about how things move. Now we are going to predict how forces can change their movement. What does the word 'predict' mean?"
We have used the word 'predict' many times before, but I want to make sure that everyone knows exactly what I mean before we begin, so we talk about it and I write our accepted definition on the board. Then I say,
"So to start today, I want you to think of a time that you were moving, maybe riding in a toy wagon or sliding down a slide or on a swing. Then, for some reason, you stopped. Has that happened to anyone? Can you tell us about it? Why did you stop?"
The reason I engage students in this conversation up front is to build background knowledge for the students who may not have experience with riding bikes or skateboards so that they can readily participate in making predictions in during the Activity section of the lesson. Communicating and sharing ideas supports Science and Engineering Practice 8.
After a few students have shared things that they remember and I have pointed out what the forces may have been that stopped or changed their motion, I say,
"During our lesson today, I am going to show you some children doing some cool things and you are going to make some predictions about what could happen. Ready??"
Then we start the activity!
For the activity, I use the recording sheets to organize my students' responses in their journals. Before we begin, I quickly show them how to use the recording sheet. Then I say,
"I am going to show you what these first boys are up to. It is pretty cool! Then, I will stop the video and I will tell you that there is going to be a force and you will make a prediction about what might happen, okay?"
It is really important that I stop the first video of the BMX bikers at :25 seconds! Then I say,
"Write down on your recording sheet the motion you saw and make a prediction about what could happen next".
After a few seconds, I invite students to share their responses, then I play the next few seconds of the video where the kid falls on his bike. I stop the video again and I tell my students to record what the outcome was. Then I say,
"What force made the boy fall?"
Although we can't be totally sure even if it was a seen or unseen force from the video, we can guess. It could have been a rock or some sand that his bike slid on, or maybe he lost his balance.
For the second video of an 8-year old skateboarder, stop the video at :24 seconds. This time, the kid doesn't fall but instead turns due to gravity. This opens up a different conversation but I bet my students can still predict his movement due to a force! I do the same thing - ask them to write down the motion and make the prediction, play the next few seconds of the video, then stop it and discuss.
This video has lots of examples of different types of motion, so I play it again and pause it to make several more predictions as we watch and we write down a few more.
The last example I show is a 6 year old girl skiiing. I stop the video at :47 seconds to ask for predictions. The girl does not fall but is shifting her weight to change the direction of her movement.
Making predictions supports Science and Engineering Practice 3, 'Planning and Carrying out Investigations'. Making observations from media to describe relationships (force and motion) in the natural world supports Science and Engineering Practice 4.
After our discussion about the third example, we are ready for the wrap up!
To end this lesson, I want to relate the predictions back to my own students' daily lives, so I ask,
"Now that you have seen lots of examples of forces changing the motion for other kids, what are some examples you can think of that have happened to you?"
Continuing to share ideas and communicate about the scientific content we have learned about supports Science and Engineering Practice 8.