• give examples that demonstrate how to change the motion of an object by giving it a push or pull.
  

Per class

• timer (classroom clock will also work for the whole group)

• Roller Coaster Conclusions Answer Key  (View)

Per student team/group of 3-4

• about 6 meters of plastic tubing

  (best bought at a hardware store - do not buy from a catalogue, it comes looped with twist ties and then the tubing is bent and won't open to allow passage of the "car")

• 1 bb

  You can buy a lunch-milk size carton of these just about anywhere - WalMart, etc.  There are several thousand in one small container.

• 2 meter sticks

Per Student

• Pencil

• Roller Coaster Investigation  (View)
• Roller Coaster Conclusions  (View)

Not Specified

• Indicators  (View)

• energy - what makes things move
• force - a push or pull
• gravity - the force that pulls us towards the earth
• friction - resistance to motion because things are rubbing together creating heat

Set-up Directions:

The teacher needs to have the tubing, bb's and meter sticks ready for student work. Copy the Roller Coaster Investigation worksheet and the Roller Coaster Conclusions worksheet for each student. Pre-determine the grouping of students. Groups should contain 3 to 4 students. A computer or computers with Internet access should be available in the classroom. Bookmark the Funderstanding Web site.

Teacher Presentation & Motivation:
The teacher will begin the class by reviewing the terms force and gravity (or teaching them, if they haven't yet been taught). Then hold a ball (any type) up in the air and ask the students, "If I drop this ball, will it bounce back up to my hand?" Let the students respond, and then test it out. You may have to do it a few times for them to see that the ball will not bounce back up to your hand. Ask them, "Why does the ball drop when you let go of it?" (You want them to say gravity pulls it.) Tell them that when something moves scientists say it has energy. So does the ball have energy? Hold it in your hand. Does it move? When you let go of the ball, does it move? It moves because of the force of gravity. The energy that is moving the ball is called gravitational energy - when something moves because of the force of gravity. So why doesn't the ball bounce back up? Why do some things bounce and some don't? Explore these questions by dropping a few different things - try to include one of those very bouncy balls (we used to call them super balls). Remind the students that if you pushed the ball down, you would be adding extra energy to the gravity - so then it would bounce back up to your hand or even farther. But even the bouncy ball will not bounce back to your hand if only gravitational energy is pulling it. Explain to the kids that some of the gravitational energy changes into heat because of friction. If the kids are not familiar with friction, ask them to rub their hands together briskly. What happens to their hands? They get warmer. Explain that when things rub together, this is called friction. Friction makes heat, which is a form of energy. So the energy due to gravity (the energy the ball has from the height that it is dropped) is changed into heat when the ball moves through the air and hits the ground and moves back up, because the ball is rubbing against air molecules and the floor (very quickly) and some heat is being made. The gravitational energy is changed into heat energy. (This understanding will help kids later (probably not in third grade) to understand the Law of Conservation of Energy - no energy is ever lost or used up, it is changed to a different kind of energy. So if I drop the ball and it has 10 units of gravitational energy when I drop it, it will only have 9 by the time it hits the floor so it can't bounce back up to its original height. (Of course, these numbers are all made up, but I find that the students relate better to the idea when I attach numbers to it. I usually draw an arm and ball on the board and show 10 at the height of the arm and 9 at the floor, explaining that the whole way down and back up again gravitational energy is being changed into heat energy.

Then ask the students: "How many of you have ever been on a roller coaster?" Allow for some time for the students to talk in their groups about their roller coaster experiences. Then ask the students: "What happens when the ride starts?" You want them to say, the car goes up. On most roller coasters, the first hill is a big one. This is to help the car get the most gravitational energy it can. Draw the slope of a hill going up, but stop at the top of the hill. Ask, "How does the car get up the hill?" They will answer with a variety of answers: chains, machines, engines, pulleys. Tell the students that scientists call energy made by machines - mechanical energy. (or chemical energy if they want to talk about the burning of fuels). Then put your chalk back at the top of the hill and say, "When you get here, you usually stop for a second and then - what happens?" Students will all say "you go down the hill." So draw the down side of the hill and ask, "What kind of energy pulls the car down the hill?" They should say "gravity!"

Then place your chalk about where the second hill might peak, at the same height of the first hill. Ask the students, "If the car came down the hill because of gravity, and no other energy was added, could the car get up to a second hill as high as the first hill?" They should say no. If not, you will need to re-teach the idea about gravitational energy changing into heat due to friction. But, students are usually ready for this question and say no. Ask one to explain why and they should say some of the energy from gravity turned into heat because of friction. Ask the students, "Where is friction happening?" They should say on the track and in the air. Ask, "How high could the second hill be?" Select a student to come up and show you on the board how high they think it could be. Ask the students if they agree or not, and let them talk about their ideas and come up with other predictions.

Tell the students, "Today we are going to design a roller coaster. The amusement park owner wants to build a roller coaster with a first hill that is 100 m. tall. They want the second hill to be as high as possible without using any machines to pull it up that second hill. We will be making roller coaster models in our classroom to find out: How high can the second hill of a roller coaster be, if the first hill is 100 m. tall?"

 

Activity 1 - Roller Coaster Investigation

Students will perform the investigation given the following student pages: Roller Coaster Investigation and Roller Coaster Conclusions. The teacher sill read aloud the procedures found on the Roller Coaster Investigation worksheet, pausing to give time for students to write their hypothesis and justify their thinking. Then students will complete the activities with their groups. Each student will turn in their own work, Roller Coaster Conclusions worksheet, for assessment purposes.

Activity 2 - Funderstanding

Students will use the Web site to apply what they have learned about roller coaster designs. Students can change the following variables online: the height of 2 hills and a loop, the mass and speed of the car, gravity and friction.  The teacher will lead a discussion, which will review the Web site and what they have learned from this activity.

Wrap Up:

Discuss the results of their investigations. Which variable seemed to make a great deal of difference on the success of the roller coaster? Which variable least effected the results? The teacher will lead a discussion that will answer the Class Challenge Question posed at the beginning of the lesson.