Teacher prompt: How did you get to school today?
Student response: Walk, rode a bike, bus, or parents drove the car.
Teacher prompt: How fast were you going? How would you measure how fast you were going?
Student response: Not very fast. Something like 20 miles per hour.
Teacher prompt: OK, and what are we trying to measure if we measure in miles?
Student response: Miles are a measure of distance.
Teacher prompt: Right. And we use hours to measure what?
Student response: Hours are a measure of time.
Teacher prompt: That is correct. When you put them together to find a speed, you will see you travel a certain distance in a certain amount of time. This is what we call velocity. velocity(v) = Distance (d)/Time (t) (v=d/t)

Teacher prompt: If we’re going to find out how fast something is moving, what two things do we need to know?
Student response: How far it went and how long it took to get there.
Teacher prompt: What are some units that can be used to measure velocity or speed?
Student response:  Miles, meters, kilometers
Teacher prompt: What do all these measures have in common?
Student response: They are all units that can be used to measure distance.
Teacher prompt: Let’s practice applying these units of measure. I need a volunteer. Let’s measure out a distance of 5 meters. You’re [student] going to walk that distance. To find the velocity, what do I need to do while the student is walking?
Student response: Measure the time!
Teacher prompt: Exactly. When I say go, walk the 5 meters. We’ll stop timing when you [volunteer] get to the end. GO! Now, how do we figure the velocity?
Student response: [Student] walked 5 meters in _____ time. velocity is how far (d) in how much time (t). 5 meters in ______ time.
Teacher prompt: That’s right. [Student] walked at a velocity of ________ m/s.

Teacher prompt: Anytime something moves, it has a velocity. For smaller and slower objects, we measure in meter per second (m/s), and for larger and faster objects, we measure in kilometers per hour (km/h). You are probably familiar with miles per hour (mph). This would be how fast a car or truck is going.

Teacher prompt: Let’s look at some other uses of knowing an object’s velocity. How many of you have ever been on a trip and asked your parents, “Are we there yet?”
Student response: I have! ME, ME, ME! Who hasn’t?!
Teacher prompt: Well, if you know how fast something is going, and you know how far away it is, what is left for us to find? HINT: Think of what two things we need to know to find velocity. If we know the velocity and the distance, what is the other measurement we need?
Student response: Time.
Teacher prompt:  That’s right! If we know how far away something is and how fast we are moving toward that place, we can find out how much longer it will take us to get there. Can someone tell me a state you would like to go to?
Student response: We want to drive to Colorado.
Teacher prompt: OK, let’s say it’s about 500 miles to Colorado from Lawrence, KS. The speed limit is 70 miles per hour. We can divide the distance (500 miles) by how fast we are driving (70 mph) to see how long it will take us to get there.
Student response: What about bathroom breaks and food?
Teacher prompt: Good catch Tommy! Let’s figure out what the time would be if we didn’t stop. 
Student response: We are traveling 500 miles at 70 mph. That means it will take about 7.1 hours to drive from Lawrence, KS to Colorado.
Teacher prompt: Now we’ll try an activity. First, roll a car or ball down a ramp, and then find the car’s velocity. Don’t forget: you need to know how far it is traveling and how long it takes.

TEACHER HINT: Have the students use the triangle below to help them solve problems on velocity. If you explain to students that all they need to do is cover up the variable they are trying to find, they will know the equation they need to solve. Then, it is just basic algebra. For example, to find velocity, students would cover up the v so that they would be left with d/t.

Teacher prompt: How many of you have ever jumped over something? How many of you have jumped on a trampoline? Did you notice anything about how fast you were moving or if you changed direction?
Student response: I changed direction. When I jump I go up, and then when I get to the top, I fall back down again.
Teacher prompt: Why don’t you fall up?
Student response: When things are dropped, they fall to the ground. If I go up, I have to come back down.
Teacher prompt: That’s right. When something falls, does how far it falls make any difference?
Student response: If something only falls a little bit, it might not break, but if I drop it from the ceiling, it probably will.
Teacher prompt: Excellent observation. Let’s try dropping some objects and see what happens when they hit the ground. (NOTE: Give students several small objects that they can use to experiment with.)

Teacher prompt: Take your tennis ball and let it drop a few times. Observe what happens as it falls and then what happens when it bounces back up. Do you notice anything about its velocity or the direction it moves?
Student response: It changes direction. It starts out falling toward the ground and then goes up after it bounces off the floor.
Teacher prompt: That’s right, but what about velocity? Is there ever a time when it is going slower or faster? (NOTE: Keep leading them and letting them bounce the ball until they see that it slows down as it rises after the bounce and then speeds back up as it falls. It may take a few minutes but be patient!)
Student response:It looks like the tennis ball slows down when it gets to the top of the bounce, and it starts to speed back up when it starts to fall again.
Teacher prompt: That’s right.Have you ever been hit in the head by something before? Does it hurt more if the object falls from just above your head or if it falls from the ceiling?
Student response: It would hurt more if it fell from the ceiling.

Teacher prompt: So the higher that something falls from, the more it would hurt your head. Why is that?
Student response: It must be going faster, and the faster something is moving, the more it will hurt when it hits your head.
Teacher prompt: That’s exactly right. So then do objects move at the same velocity all the time? For example, if I roll a ball across this table, will it stay at the same speed?
Student response: No, it will slow down or maybe stop.
Teacher prompt: Right again! This means that the velocity is changing. We call a change in velocity, acceleration. If you’re sitting in a car at a stoplight, and the light changes to green, what happens?
Student response: The car starts moving and keeps getting faster.
Teacher prompt: Correct! When something speeds up, we call that acceleration. The gas peddle in the car is sometimes called the accelerator because it helps the car go faster. If an object slows down, we call this negative acceleration, or deceleration.

Teacher prompt: We’ve now covered velocity, which is how fast something is moving. Since things don’t always travel the same velocity, objects have to speed up or slow down. What is the change in velocity called?

NOTE:  Keep emphasizing that acceleration is something speeding up, something slowing down is said to have negative acceleration, or deceleration. Don’t worry so much that it is also any change in direction.

Student response:acceleration.
Teacher prompt: What about when you roll something down a ramp, does it have the same velocity all the way down? Give it a try.
Student response:It speeds up as it goes down.
Teacher prompt: Now try to roll a car up the ramp. What happens?
Student response: It slows down and then starts rolling backwards.
Teacher prompt: Correct! The car speeding up as it goes down the ramp is called ________?
Student response:acceleration.
Teacher prompt: And the car slowing down is called _______?
Student response: Negative acceleration or deceleration.
Teacher prompt: OK. What does this mean for objects that are falling?
Student response:The higher something falls from, the faster is goes.  It accelerates.

Teacher prompt: How many of you have ever lifted an object and thought to yourself, “Wow, this is really heavy!”?
Student response: I have.
Teacher prompt: What if I told you, you could easily lift that same object if I flew you to the moon?
Student response: Prove it! (Note: You can pretty much count on this response.)
Teacher prompt: Let’s take a look at these pictures of some astronauts living and working in space. You will notice that they are moving very large objects around without much trouble at all. Yet here on earth, even the strongest person probably couldn’t lift something the size of a refrigerator. How can they do it in space or on the moon?
Student response: You’re the teacher, you tell us.
Teacher prompt: Let’s see if anything about those objects changed as they went from here on earth to the moon.

Teacher prompt: Let’s take some objects and observe how much they weigh. We’re not going to use numbers; let’s just feel how easy or difficult it is to lift the objects. (Give students time to lift each object and describe whether they are easy or difficult to lift.)
Student response: This is the hardest to lift because it’s the heaviest. This one is the easiest to lift.
Teacher prompt: Now put those same objects in this bucket of water. Keeping the objects under water, try to lift them now. Do they feel the same or different? (NOTE: I would hesitate getting into the topic of buoyancy since all we are trying to show is that just because there is a weight change doesn’t mean the mass does. We are trying to get the students to see that mass doesn’t change.)
Student response:The objects feel a little bit lighter.
Teacher prompt: So the weight changed. Did anything else change about the objects? Do the objects look different?
Student response: They look a little different when they’re under water, but the objects didn’t change.
Teacher prompt: Good observations. So the weight changed, but the mass of the objects did not.

Teacher prompt: Even though the weight of an object changes, the mass does not. The amount of material, matter, or stuff in an object stays the same. For example, a bowling ball is solid. Whether you lift it from the ground or you lift it underwater, it has the same mass. You’re not going to add anything to the inside of the ball; therefore, the mass will not change.

Teacher prompt: Think back to the pictures of the astronauts. Did you happen to notice how much heavy equipment they were wearing? Each suit weighs almost 200 pounds. It would take a lot of work to carry that stuff around here on earth all the time. Yet they walk around and jump like it’s no big deal. Why is that?
Student response: The astronauts and the suits don’t weigh as much on the moon. They weigh more here on earth.
Teacher prompt: Did the astronauts all get smaller on their way to the moon? Did their suits all of a sudden lose pieces?
Student response:No, the astronauts and the suits are the same, but there is less gravity on the moon.
Teacher prompt: That is correct. There is less gravity on the moon. Your weight is simply gravity pulling down on you. This is called the force of gravity, which we will talk about shortly. So yes, they weigh less, but what happened to their mass?  Did anything about the astronauts or their suits change on the way to the moon?
Student response: No, so that means their masses stayed the same.
Teacher prompt: That’s right, and what is mass?
Student response:The amount of stuff or matter in an object.
Teacher prompt: Yes, I call this “how much stuff.”

Teacher prompt: The book on this desk has not moved since class began. Why has it stayed still?
Student response: Nothing has made it move.
Teacher prompt: Right. What can we do to make it move?
Student response: We could push it, pull it, shake the desk, lift it, etc.
Teacher prompt: Correct. Something must be done to the book for it to move. Any push or pull on an object is called a force. In order for something to move, something else must push or pull on it.

Teacher prompt: Let’s see if we can get these objects to move without physically pushing or pulling on them. Try to move these without touching them. Do any of them move without you touching them?
Student response: If I drop something, or if I blow on something, it moves.
Teacher prompt: That’s true, but just because you can’t see it doesn’t mean that something else isn’t pushing or pulling. What might push an object if you are blowing on it? 
Student response: Air comes out of our mouth if we blow on something. Air could push it.
Teacher prompt: That’s correct. Air can push an object. The wind pushes things around all the time. What might pull an object as it falls to the ground?
Student response: Everything falls if you drop it. gravity makes it fall.
Teacher prompt: Right. gravity is a force that pulls objects toward the center of the earth. So as you can see, just because you can’t see it, invisible things can still push or pull on objects.

Teacher prompt: We already know that a force is any push or pull on an object. This is extremely important to our next topic, Newton’s Laws of Motion.Let’s take a look at how force works by experimenting with some smaller objects that we can use in the classroom or you can try at home.

Teacher prompt: A force is any push or pull. Anytime something moves, there is a force present. But sometimes you push or pull on something, and it doesn’t move. Why is that?
Student response: Maybe it’s too heavy.
Teacher prompt: That’s right. But you are still exerting a force even if it doesn’t move. Let’s look at the difference between a golf ball and a bowling ball. In order for an object to move, we must apply a force. Which one is harder to push and why?
Student response: The bowling ball is harder because it’s heavier.
Teacher prompt: Correct again. We say that when something is heavier, it has more mass. Remember, mass is the amount of matter (stuff) in an object. The bowling ball has more stuff in it. In order to get a larger object moving, we must apply a larger force. Try experimenting at home with objects of different masses.  Make sure you have your parent’s permission, and don’t break anything. (NOTE: You might remind them that mass is not the same thing as weight. Make sure to always use the correct term so they don’t get confused.)

Teacher prompt: Place a playing card or index card on top of an empty cup.  Then place a coin on the center of the card. Now, flick the card off the cup with your finger. (Take a few minutes to make sure everyone has a chance to try this activity.) What happens to the card and to the coin?
Student response:The card flies away, and the coin fell in the cup.
Teacher prompt: Why didn’t the coin fly off with the card? Remember, we’re looking at forces. To what object did I apply a force?
Student response:The card. Is that why the penny didn’t fly away like the card?
Teacher prompt: That is correct. Let’s take a look at another activity.

Teacher prompt: If you roll a marble across a level surface such as the floor, what path will it take? In other words, will the ball or marble zigzag, go straight, or curve?
Student response:If I roll it straight, it should go straight. If the surface is not level, it may curve a bit.
Teacher prompt: Let’s find out. (NOTE: Break the students up into small groups, and have the groups roll marbles back and forth.) What path did the marble take?
Student response: It went straight.
Teacher prompt: Yes. That was not surprising though. Now let’s change things up a bit. If we rolled the marble across the floor toward a book, what would happen when it hit the book?
Student response: It would bounce off the book and roll in the other direction.
Teacher prompt: Let’s try it. (Have the groups hold a book up at a 90-degree angle and roll the marble to it.) What path did it take?
Student response: It bounced off and rolled a different direction.
Teacher prompt: Again, this is not surprising. But, why did the marble change direction?
Student response: The book got in the way. It hit the book and bounced off.
Teacher prompt: Right. So it would be fair to say the book forceD the marble to change direction. Notice that the marble went straight until it hit something and changed direction.

Teacher prompt: Think back to our initial discussion of force. A force is any push or pull on an object. So, if a soccer ball is sitting motionless in the grass, will it start to move on its own?
Student response: No, a force must be applied, like someone kicking it. If no one touches it, it won’t move.
Teacher prompt: That is correct. This is an excellent example of Newton’s First Law of Motion, also called the Law of inertia. The Law of inertia says that an object at rest will stay at rest unless acted on by a force. That soccer ball will never move unless something acts on it. Now think about the activity with the marbles. Newton’s First Law also says that an object in motion will remain in motion unless acted on by a force. The marble was rolling in a straight line until what?
Student response:It was rolling in a straight line until it hit the book. The book applied a force, causing the marble to change direction.
Teacher prompt: Excellent! Let’s take another look at Newton’s First Law.

Teacher prompt: We’re going to use the marbles again, but this time we are going to roll them along the inside of a styrofoam plate. What path might the marble take this time? 
Student response: A circle.
Teacher prompt: Try it and find out. Roll the marble around the ridge of the plate. What path did it take?
Student response: A circle.
Teacher prompt: Right again. Why did the marble go in a circle instead of going straight?
Student response: It went around the edge, and the edge of the plate kept it in a circle.
Teacher prompt: So in other words, the edge of the plate forceD the marble to go in a circle. Let’s change it one more time. Cut out a ¼ of your plate like you were cutting a ¼ piece of pie or pizza. Now you should have an opening. What path will the marble take now if you roll it along the inside of the plate? Let’s write some predictions on the board. (A. It will continue in a curved path and end up back on to the plate; B. It will roll off the plate but continue on a curved path; C. It will roll off the plate and go straight; or D. It will roll off the plate and curve away from the plate.)
Student response: Most will say it will follow a curved path but miss the plate, letter B, but you may get all answers.
Teacher prompt: Try it and see. (Students will find that as the marble reaches the cut out part of the plate, it will roll off the plate and go straight, letter C.)  

Teacher prompt: Why did the marble go straight? Why did it not continue in a curved path?
Student response: The edge of the plate was missing. (NOTE: You may not get this answer right away. Keep probing by reminding the students that the edge of the plate kept the marble in a circle in the previous experiment.)
Teacher prompt: Remember the last activity when we said the edge of the plate forceD the marble around in a circle. Well, part of that edge is gone now. Because there was nothing to force the marble to keep rolling around the circle, the marble went straight, just like the first part of the activity. This is part of Newton’s First Law of Motion. Another way to say this is: A moving object will continue to move in a straight line unless a force changes its direction.

Teacher prompt: Now let’s tie an object to the end of a string. Make sure the area around you is clear of other people and begin twirling the object around in a circle. (Give students time to do the activity before continuing with the question.) What force is keeping the object moving in a circle?
Student response: I am the force that keeps it moving in a circle. (Answers will vary but keep probing the students until they realize they are the force.)
Teacher prompt: By holding the string, you are the force keeping the object moving in a circle. Now practice swinging the object and letting it go so that the object moves in a straight line. Make sure no one is standing in front of you when you let it go. (Give students enough time to do the activity.)When you let go of the object, why does it stop going in a circle?
Student response: The object no longer goes in a circle because the force (me) that was making it move in a circle is no longer there.
Teacher prompt: That’s correct.

Question 1: The Olympic track event “the hammer throw” requires the athlete to swing a weighted ball, which is on the end of a chain, in a circle over his or her head. The athlete swings the ball over his or her head, then releases it, trying to throw it as far as possible. In order to count, the ball must land between the lines on the playing field. At what point does the athlete need to release the end of the chain in order to make sure the ball lands in the marked area (between the lines on the field)?

Student response: The athlete swings the ball around in a circle. In order for the ball to land in the marked area, the ball must be released between the lines. Once it’s released, it will travel in a straight line since there will no longer be a force holding the ball in a circle around the athlete. 

Question 2: In your own words, write a definition of Newton’s First Law of Motion.

Student response:  Responses will vary but should include an understanding that an object in motion will stay in motion unless a force acts on it, that an object at rest will stay at rest unless a force acts on it, and that an object will go straight unless a force causes it to change motion.

Question 1: What path will a marble follow if you roll it ACROSS a ramp? Explain your answer.

Student response: The path will be a curved path with the ball curving toward the bottom of the ramp because gravity is FORCING it in that direction.

Question 2: What path will a marble take if you roll it straight up a ramp? Explain your answer.

Student response: It will go in a straight line up the ramp, stop, and roll back down the ramp in a straight line. The force of gravity will change the marble’s motion.

Teacher prompt: Today we’re going to take a look at Newton’s Second Law of Motion. We’re going to begin by looking at how much force you need to push something. First, let’s review a few things. What are mass, acceleration, and force?
Student response: mass is how much stuff is in an object. acceleration is the speeding up or slowing down of an object. force is any push or pull.
Teacher prompt: Very good. Now I need a volunteer to push this rolling chair.  Take note of how easy or difficult it is to push.
Student response: It’s on wheels so it moves very easily.
Teacher prompt: I need another volunteer to take a seat in the chair. Now try pushing the chair with the student in it. Again, note how easy or difficult it is to push the chair.
Student response:It’s harder because there is more weight.
Teacher prompt: Did we do anything to the chair? 
Student response: All we did was add mass by having someone sit on the chair. 
Teacher prompt: So if we add mass, what could we say about the force needed to accelerate (begin moving) the object?
Student response: The more mass we have, the more force is needed to push the object.
Teacher prompt: That is absolutely correct!

Explore:
Teacher prompt: Remember the story about the “Three Little Pigs”? In the story, the wolf was “huffing and puffing,” trying to blow three different houses down. Today we are going to study some of the science behind why he was able to blow two of the houses down but not the third. (Divide the students into groups of three or four.) One member of each group will be the wolf. Practice “huffing and puffing” into the straws. Don’t blow your hardest, but instead make a short puff that you can repeat with the same strength several different times.Place the ping pong ball on the floor in front of you. Then the “wolves” should move the ball by blowing on it through the straw. Measure the distance the ball rolls. Repeat this two more times, making sure to blow with the same strength each time.
Student response: We’ve done it three times and wrote down the measurements.
Teacher prompt: Good. Now find the mean (average) distance the ball rolled.
Teacher prompt: Let’s try it using the golf or tennis ball instead of the ping-pong ball. Remember to blow with the same strength that you did when using the ping-pong ball. Repeat this three times, measuring the distance each time. Then find the mean distance the ball rolled.Which ball rolled further and why?
Student response: The ping-pong ball rolled further because it was lighter.
Teacher prompt: Yes it was lighter, but there is something else we’ve been talking about related to Newton’s Laws. Is there another reason why it rolled further?
Student response: The ping pong ball has less mass so it didn’t take as much force to move it.
Teacher prompt: That is correct! Now we are going to try the same thing again with the ping-pong ball and the tennis ball, but this time, make the puffs a little harder. What are we changing?
Student response:We are changing the amount of air hitting the ball. There is more force.
Teacher prompt: That’s right. Can anyone predict what might happen?
Student response: If there is more force, the balls should roll further.
Teacher prompt: That’s right again. Let’s give it a shot. Remember to run three trials with each ball and find the mean.
Teacher prompt: Let’s discuss the results of your trials. Was your prediction correct? Did the ball roll further this time?
Student response: Yes. 
Teacher prompt: Why?
Student response: There was more force.

Teacher prompt: These activities have just provided examples of Newton’s Second Law. This law shows the relationship between mass, acceleration, and force. Let’s take a closer look. Let’s look at the trials with the ping-pong ball first.  Think about the trials when you didn’t puff quite as much and the others when you puffed harder. What did you notice about the motion of the ball?
Student response: The ball rolled faster when there was a stronger puff.
Teacher prompt: That is correct. Did anything about the ball itself change? Did the mass stay the same?
Student response:Nothing changed about the ball. The mass stayed the same.
Teacher prompt: If the mass stayed the same, and we applied a larger force, what can you say happened to the acceleration?
Student response:The acceleration increased.
Teacher prompt: That’s right again. We say that if the mass stays the same but the force increases, the acceleration will also increase. We can also say that the opposite is true. If there is less force on the same mass, the acceleration will decrease. Now let’s take a look at the differences in the ping-pong ball and the tennis ball. Let’s use the trials with the first puff, the lighter puff. Which ball rolled faster?
Student response: The ping-pong ball. It has less mass.
Teacher prompt: That’s right. The ping-pong ball has less mass so it doesn’t need as much force to get it moving. What do we call it when an object is speeding up, in this case from not moving to moving faster?
Student response:acceleration.
Teacher prompt: Yes, and according that definition, which ball had the most acceleration? Which ball got moving faster?
Student response: The ping-pong ball.
Teacher prompt: Correct again. We can say that using the same force, the ball with less mass will accelerate more. The ball with more mass and the same force will not accelerate as much. One part of Newton’s Second Law states “a change in mass (the different balls) and/or a change in force (how hard the students blew) changes the motion (the acceleration) of an object.” There are several things involved with this law. The more mass an object has, the more force it takes to move it. The more force exerted on an object, the more it can change its motion (be accelerated). (NOTE: Although much of this is intuitive to most students, different combinations of changes can make it difficult for them. The use of examples can help them to understand the differences.)

Teacher prompt: We have been talking about the relationship of mass, acceleration, and force. We have also talked about how gravity pulls objects toward the earth and causes them to move faster. The higher I drop an object from, the faster it will fall until it hits the ground. Let’s take three different coins (examples: nickel, dime, quarter, etc.).  First, let’s use the balance to find the mass of each of the coins. Now, we’ll place all of the coins at the end of the table. We’re going to use the meter stick to make sure that all of them get pushed off the table at the same time. Watch carefully as they hit the floor. Which object hits first? (Try this at least three times.)
Student response: They hit at the same time.
Teacher prompt: That is correct. When we measured the mass, were they all the same?
Student response:No.
Teacher prompt: OK, but they all hit at the same time. This is what we call an object in free fall. The only thing pulling those objects toward the earth is gravity. gravity is causing those objects to accelerate. gravity, on earth, is constant. Those objects were being accelerated toward earth all the same. We know their acceleration was the same, and the mass of each was different. What is missing?
Student response: force.
Teacher prompt: That’s right. If we have objects that have the same acceleration, but different masses, what happens to the force? Think back to the ping-pong ball and tennis ball. Which object would hurt more if it hit you in the head?
Student response: The object with more mass would be falling with more force. The object that has more mass would hurt more if it hit you in the head. It would hit you with more mass.
Teacher prompt: That’s right.

Question 1: In horse races, the riders are usually very small, light-weight people. Why would a rider who weighs less have an advantage over a rider who weighed more?

Student response: It takes less force for the horse to run around the track with a light-weight rider.

Question 2: In your own words, write a definition of Newton’s Second Law of Motion.

Student response: Responses will vary but should include that the more force that is exerted on an object, the faster and further it will go, and that the more mass an object has, the more force it will take to move it.