LESSON CONCEPT

REVIEW

The POE DemonstrationThe purpose of this activity is to examine differing types and structures of activities within the context of the inquiry cycle and see how these might be used to support inquiry process skills and content learning in an inquiry-based curriculum unit.

The following example lesson is representative of other lessons of this type. Please review this lesson to address the following questions, which you will then post in this discussion thread:

1. Briefly describe what you think the primary focus of this TYPE of lesson is (in the context of the inquiry cycle). Don’t focus on the content of this lesson specifically, but the type of thinking and learning that this type of lesson encourages.

2. What are the critical components of this type of lesson? What seems to need to be included in the lesson to make it work?

3. When would this type of lesson seem to work best in the learning cycle?4. What aspects of instruction with this type of lesson might a teach need to consider

regarding pacing, media, grouping, assessment, materials, or other aspects of teaching?

5. What three things might you suggest to a teacher who is considering using this type of lesson?

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Lesson 3 Objectives

1st law: Objects continue in their state of motion, Force is needed to change motion Using Newton's 1st law as defined by the class, students explain a real life example of continued state of motion (rest or motion) and an example of changed motion. Assessment criteria Explanation will identify objects' state of motion and whether the object continues or changes motion. Appropriate force will be identified for objects that change motion. Absence of appropriate force will be identified for objects that continue their state of motion. Observations (evidence) with ideas are used to develop explanations of phenomena Using observations of ballistic cart demonstrations and ideas develop during previous demonstrations (prior idea for the first demonstration), student explain their observations. Assessment criteria Explanations will integrate both observations of the phenomena and ideas developed up to that point. (Note: the student sheet "Ballistic Cart Demonstrations" supports this.) Lesson 3 Moving Objects

The ballistic cart

Display The question “Why did I keep going when my bike stopped?” and the public posting of the question provides students with a focus and a reflection point.

Student Sheets: Moving Objects

Post the question “Why did I keep going when my bike stopped?” on the chalkboard or bulletin board. Have each student write an initial response to the question based on his or her personal experiences. Restate the question “Why did I keep going when my bike stopped?” and have a few students share their initial responses with the class. After students have shared their responses, set-up the day’s task.

“In order to help us understand the question “Why did I keep going when my bike stopped?” we are going to make predictions and observations of a number of demonstrations using a cart and ball. The cart represents your bike and the ball represents you. As each demonstration is done you will first make a prediction of what you think will happen, then you will observe what actually happens and try to give an explanation of what you observed. As you make your predictions, observations, and explanations you will write these on your sheet.”

Direct the students’ attention to the student sheets where they will be following along.

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POE The prediction, observation, and explanation cycle aids students in understanding the concepts that are being introduced. The prediction should include what they think will happen and why. The observation should be a paragraph or a diagram of the event. The explanation is why the event happened the way it did.

Ballistic Cart Demonstrations This session consists of a series of teacher lead demonstrations. Each demonstration illustrates an important aspect of Newton’s 1st law. The demonstrations performed in this order leads students to gradually develop their understanding of the concept. Completing one demonstration, including making explanations for what is observed, gives students knowledge necessary to make meaningful predictions for the next demonstration. Each demonstration follows that same Prediction, Observation, Explanation, (POE) cycle outlined below.

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The Prediction, Observation, Explanation Cycle

Predictions

Tell the students what you are going to do in the demonstration. Ask the students to make a prediction about what will happen to both the cart and the ball. Have them write down their predictions and why. Discussion: After all have written their predictions choose a student to share their prediction. Ask them the reason for their prediction. Ask for any different predictions and explanations. It is not necessary that the predictions agree, but students have to offer an explanation for their predictions

Observations

Perform the demonstration as described in each section and allow students to observe. Repeat the demonstration if necessary. Have the students record their observations by writing a description or drawing a diagram of what they see. Explanations

Have students write an explanation that expresses their ideas about what they observed. Explanations should address why each the cart and the ball moved as they did. Have a few students then share their explanations with the class. Have the students also share if their prediction matched their observation and why? Concept Identification: Work with the students and their explanations to develop a more general and scientifically appropriate understanding. Have students talk about their explanations. Ask students to compare the various explanations. Did the cart move? Why not? Did the ball move? Why not? Relationship to Question: Relate this back to the driving question by asking What if I used a bicycle instead of a cart or any other object what would happen?

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Demonstrations This first demonstration illustrates an important part of Newton's 1st law even though it may seem simplistic. Because this demonstration is simple, this is a good time to help students learn the POE process, which may be new to them.

Multiple ideas Use the multiple occasions of student sharing in class as an opportunity to allow many students to publicly express their ideas by inviting different students to speak each time.

Scaffolding After a concept is introduced, place the conclusion on the board for each demonstration. This will help students visualize the development of the law as each demonstration is performed.

Practice These demonstrations are an opportunity for students to practice drawing forces. Student can draw arrows indicating the forces on the ball or on the cart as part of their predictions. They can use these drawings as they

The Demonstrations Hand out the “Moving Objects” Sheets.

Demonstration 1 Cart and Ball at Rest

Prediction Do this first demonstration with the students as an example of a POE. Also, try to tie in with what they learned about force in the last class period. This and the next demonstration are simple and should only take a few minutes. They should not be skipped however as they connect the concept of force to motion and illustrate an important part of Newton's first law. Tell the students that you are going to place the cart with the ball inside on the demonstration table. Ask the students to make a prediction about what will happen to the cart and the ball if it is left as is. What will happen to the cart? The ball? Have them write down their predictions and why. Students should draw arrows on the diagrams to represent the forces acting on the ball and on the cart. Discuss student predictions. For this first demonstration, tell them your prediction as an example. Remember to use experience to give a reason for your prediction. (I predict it will not move because I have seen toy cars sitting on the table and they did not move.) Observation

Place the cart on the table with the ball inside and observe for a short time. Have the students record their observations by writing a description or drawing a diagram of what they see.

ballistic cartball

table

Explanation

Explanations should address why cart did not move and why the ball did not move.

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try to explain their observations.

Real world connections Press students to base their predictions on their everyday experiences. For example a student may predict that the cart will not move because they have seen many objects such as books etc. not move when they are sitting on a table.

The Ball Students may have difficulty thinking about the ball inside the chimney because they cannot see it. Use this observation time to let students look inside the chimney as the cart sits on the table.

Terminology While we use the terms “object,” “act upon” or “at rest,” students will most likely not use these terms, rather they will use terms like “thing,” “touch or hits” or “won’t move.”

“The cart and ball do not move because there is no unbalanced force acting on either.”

Discuss with students all the forces acting on the cart. Use the force diagrams to help students identify these forces. See if each force can be matched with an equal opposite force and therefore cancelled out. Gravitational force is pulling downward and the table is pushing upward. Concept Identification: An object at rest stays at rest if no unbalanced force acts on it. Here students can generalize their explanations for why this cart does not move to why objects in general do not move. Have students give examples of other cases in life when things do not move. Remind them to say in reference to what the object is not moving. Questions to guide concept identification: Have students talk about their explanations. Ask students to compare the various explanations. Did the cart move? Why not? Did the ball move? Why not?

Relationship to the Question: Relate this back to the question “Why did I keep going when my bike stopped?” by asking

• What if I used a bicycle instead of a cart or any other object initially at rest? What would happen?

• Why didn't the egg and cart move when I was holding them?

Clarification Expect students to use the term “push” or “pull” and not “force.” If they do use h “f ” k h

Demonstration 2 Cart and Ball In Motion Together

Now that the class can agree that the cart and ball did not move ask them why and what would be needed for it to move. Someone should bring up the fact that the cart needs to be pushed or pulled. Use this as an opportunity to relate this to pushing and pulling activities yesterday. Again this is simple and quick but

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the term “force,” ask them to explain what they mean.

Frame of Reference Students will need to see inside the cart to see the ball staying with the cart. Remind them that you are using the classroom as the frame of reference. In the next demonstration students will not be able to watch inside the cart because the spring will be release popping the ball upward.

Gravitational force Gravitational force is a special case but objects move under the influence of this force in the same fashion as they move due to any other force. Gravitational force is special because this force is always downward.

Balanced Forces Students may say the cart is “parked,” meaning that since gravity is all around us, it must be pointing in from all directions and keeping the cart in place. Make sure they understand what the forces are that are acting on the cart and in

important demonstration. This is also related to the egg and cart beginning to move down the ramp. Prediction Pick up the cart and ball and place it back down on the demonstration table. Tell the students that you are now going to push or apply a force to the cart with the ball inside. Ask the students to write down their predictions of what will happen to the cart and the ball and why. Have students draw arrows on the diagrams to represent the forces acting on the cart and on the ball. Discuss student predictions and force diagrams. Observation Place the cart with the ball inside on the table and give it a push. You will probably need to catch the cart before it rolls off the table. Remind the students to observe the cart and ball through out its motion and to record their observations by writing a description or drawing a diagram of what they see.

apply force

initial position

final position

Explanation Explanations should address why both the cart and the ball moved and why they moved together. Have a few students then share their explanations with the class and if their prediction matched their observation and why? Concept Identification: An object at rest stays at rest until an outside force acts on it. Questions and points to guide the concept identification:

• Did the cart move? Did the ball move? • Did they move together or separately? • When did the cart begin to move? • When was a force applied?

Relationship to the Question When you and your bike are at rest, h d t th bik t ? (Y l f h t

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which directions those forces are working.

how do you get the bike to move? (You apply a force or a push to the pedals, which puts you in motion). When the egg and cart where placed on ramp why did they begin to move? (You removed your hand, thereby removing the force that balanced the force of gravity on the egg and cart. The egg and cart were now subjected to an unbalanced force and therefore began to move.)

Reading at Home

Why do I keep moving when my bike stops? - Why is it not moving?

Motion and Friction Students often have a hard time understanding that an object in motion will stay in motion because their daily lives lead them to believe otherwise. This demonstration is important in pointing out that the reason why the object did not stay in motion was because a force (frictional force) acted on it. Had there been no force to act on it, it would have indeed stayed in motion.

Demonstration 3 Friction

You may choose to do this demonstration here if a student mentions that things do not keep moving in the real world or wait until later to do this one. Prediction Pose the question “What would happen if the cart were placed on the floor and given an initial force (push)?” Have the students write down their predictions again. Have students draw arrows on the diagrams to represent the forces acting on the cart and on the ball. Discuss student predictions and force diagrams. Observation Place the cart on the floor and push it. Remind the students to observe the cart and ball throughout its motion and to record their observations. The cart with ball inside should stop eventually due to friction between the wheels and the floor and between the axles and the cart. You may want to practice the amount of force you give to the cart before hand so that the cart will travel as far as possible but not hit the wall. If there are different surfaces available such as carpet versus tile floor, this demonstration can be repeated on each surface. There will be more friction on a plush surface and the cart will slow down and stop more quickly.

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Explanation Students’ explanations should address why the ball and cart stopped and where was the force. Concept identification: An object in motion stays in motion unless acted on by an outside force. Questions and points to guide the concept identification: Why did the cart stop? Where is the force? Can you imagine what would happen if there was no friction? (Continued motion) Does this ever happen? (In space) Reflect back on demonstration #2. During this demonstration, a force or push put the cart and ball in motion. What stopped the cart and ball from falling off the table? What force was applied to the cart and ball? Relationship to the Question If you are riding your bike, what force or push keeps you in motion (peddling)? If you stopped peddling, what would happen and why? You would stay in motion until you slowed down due to friction between the moving parts of the bike. When you are peddling, the peddling force is equal to the friction force so you stay in motion.

Prepare Practicing this demonstration in advance in order to get the timing correct is highly recommended. Tips:

• Use a level surface • Push the cart firmly • Snap the string

quickly and straight back.

Demonstration Students will probably ask you to repeat this demonstration. It is engaging and the result is unexpected.

Demonstration 4 Cart and Ball in Motion Separately.

Up until now the demonstration were simple and quick. This demonstration is much more interesting and unexpected. Plan to spend more time on each step of this one. Prediction Tell the students that this cart has a spring in it and that when you pull the pin out the ball pops up. Show them how this works with the cart standing still. The ball will land back in the cart. Tell them that you are going to push the cart and while it is moving, you will pull the pin. Ask them to write down their predictions of what will happen. What will happen to the cart and the ball before, during, and after the ball is in the air? Have students draw arrows on the diagrams to represent the forces acting on the cart and on the ball. Discuss student predictions and force diagrams. Observation Place the cart with the ball in it at one end of the table. Push the cart and while the cart is moving pull the pin out with a quick straight snap of the string. The ball should pop up and land back

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Unexpected Results These observations will surprise students. Many might initially think that the ball will fall behind the cart. They might also think the ball can land in the cart if it is going slowly enough but if it were going faster, the ball would fall behind it.

Clarification Students will have a difficult time developing an appropriate explanation for these observations. Allow time for students to express their ideas. Help them to clarify their ideas by asking them to explain in greater detail. You might want to paraphrase their comments. Ask other students to add on to what was said. See if students can express their ideas in a number of different ways.

Further Development An additional demonstration that may help students to think about the ball moving with the cart would be to place the ball on the cart outside of the chimney. When you push the cart, students will be able to see the ball stay in position relative to the table or move backward relative to the

in the cart and both the cart and ball will continue to move forward together at the same speed. Remind the students to observe the cart and ball through out its motion and to record their observations.

apply force

initial position final positionrelease ball

This demonstration can be repeated at various speeds.

Explanation Explanations should address what happened to both the ball and cart and why. Concept Identification An object in motion stays in motion unless acted on by an outside force. Questions and points to guide concept identification: Were they surprised by their observations? WHY? Why did the ball land in the cart if the cart keeps moving after the ball is released? Did the ball keep moving also? Did the cart or the ball move faster? Did they move at the same speed? Was there a force on the cart or the ball? Try to identify each force and direction of the force on the ball and on the cart. Mini-Take Home Assignment If students have trouble visualizing the ball staying with the cart and still think the ball should fall behind the cart or that the ball might land behind the cart if the cart were going faster, the can try a little experiment on their own: Drop a ball in their lap or toss one up gently and while riding in a car. Will it land behind them or in their lap or hand? Relationship to the Question If a bike and you are moving along and you were to jump up off your bike straight up where would you land relative to the bike?

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cart. Also, stop the cart and see the ball roll forward. This is like the egg and the cart hitting the barrier.

Reading at Home Why do I keep moving when my bike stops? - Why is it moving?

Demonstration 5

Cart Stopped While Ball is in the Air

Horizontal Forces This demonstration is used to illustrate the affect of horizontal forces. There is a vertical force on the ball. This force is due to gravity and pulls the ball downward (but not horizontally) with the cart.

Practice Practicing this demonstration in advance in order to get the timing correct is highly recommended.

Explanation The ball was moving when it was released and continued to move forward. The cart was moving until a force was applied causing it to stop.

Prediction Tell the students you are again going to release the ball while the cart is moving but the cart will be slowed down while the ball is in the air. Have students draw arrows on the diagrams to represent the forces acting on the cart and on the ball. Discuss student predictions and force diagrams. Observation Use a block or other obstacle in the path of the cart to slow or stop the cart soon after the ball is released. Push the cart. Release the ball while the cart is moving just before it reaches the obstacle. Alternatively, you can use a high friction surface such as carpeting to slow the cart quickly but not the ball. The ball will land in front of the cart. The ball was moving when it was released and continued to move forward, no force was applied to the ball. The cart was moving until a force was applied.

initial position barrier

apply force

release ball

final position

Explanation Explanations should address why the cart and ball moved, why the cart stopped, and why the ball landed ahead of the cart. Concept Identification An object in motion stays in motion

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unless acted on by an outside force. Questions and points to guide concept identification: What did they observe? Was there a force on the cart? (Yes--from the hand when pushed and the obstacle) What did the force from the obstacle do to the motion of the cart? (Slow it down). Was there a force on the ball? Did the motion of the ball change? Does this match with our law we have written on the board? Objects in motion stay in motion. For the ball yes, what about the cart? It was moving then stopped? Why? Should we add the affect of forces to our rule? Relating back to the driving question “Why did I keep going when my bike stopped?” What happens if there is an obstacle in the road that stops your bike? Explain what would happen to you and the bike.

Final Concept Integration

Work with the class to construct a final general scientifically appropriate understanding that integrates all of the conclusions to the demonstration thus far. An object in motion stays in motion or an object at rest stays at rest unless acted on by an outside force. Tell the students that this Newton’s 1st Law of Motion

Reading at Home

Why do I keep moving when my bike stops? - Changing motion with force.

Demonstration 6

Cart Speeds Up While Ball in Air

Time Saver This demonstration is optional. It can be included if time allows. It is a nice extension to students’ understanding of Newton's

This demonstration is more difficult to do. You might choose to talk through this one rather than do it. Prediction Tell the students that you are now going to increase the speed of the cart when the ball is released. Remind students to keep in mind the rule they have just established. Have students draw arrows on the diagrams to represent the forces acting on the cart

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1st Law.

POE’s Students have written many predictions, observations, and explanations. It is important that students know that their work is valued. It is also an opportunity for students to receive comments that will improve their work in the future.

Correcting One way to manage the large job of many student sheets to read is to focus on one or two concepts. For example you could look at students’ work to see if they are using the previous demonstration to make a prediction for the next demonstration. Next time students complete POE’s you could assess their ability to use observations to make explanations.

and on the ball. Discuss student predictions and force diagrams. Observation Start the cart moving. Release the ball. After the ball is released, increase the speed of the cart. This can be done by using a string attached to the front of the cart looped over the edge of the table on a pulley with a weight attached on the end of the string. The string with the weight attached will continue to pull the cart (applying a force) causing the cart to move faster and faster. The ball will land behind the cart. Another way to increase the speed of the cart after the ball is released is to pull the string while the cart is still at rest. Then immediately give the cart a push. In this case the speed of the cart increases from zero to some speed. The ball was released before the push and therefore is not moving horizontally. Explanation Explanations should address why the cart and ball moved, why the cart moved faster, and why the ball landed behind the cart. Concept Identification: An object in motion stays in motion or an object at rest stays at rest unless acted on by an outside force. Questions to help guide the concept identification: Was there a force on the ball? Did it move faster or slower? Did the cart move faster or slower? Was there a force on the cart? Why did the ball land behind the cart? Does this agree with our rule (on the board)? Ask the students to describe a similar situation with them and their bike. Extension. What would happen if the cart began moving in a different direction (turned) after the ball was released? Apply Newton's 1st Law to Real World Situations

You can further reinforce Newton’s First Law by applying it to everyday situations such as.

• Jumping out of a train like in movies • Dropping things out of the car while it is moving • Objects sliding forward when the car stops • Things landing in your lap when dropped while the car is

moving

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Student Sheet: Newton's 1st Law in Everyday Situations

Home session Assign students the “Newton's 1st Law in Everyday Situations” sheet. This sheet identifies everyday situations students will be familiar with. Students are asked to make predictions for, observations of, and explain each situation based on their understanding of Newton's 1st Law. This is a home session that parents can work on with their child.

Reading at Home

Why do I keep moving when my bike stops? - What did you learn?