##
* *Reflection: Staircase of Complexity
Newton's 3rd Law: Skateboard Activity - Newton's Laws Expo (8 of 9) - Section 3: Student Activity

As part of this activity, I talk to the kids about how rocket engines work. If a rocket shoots particles in one direction the rocket travels in the opposite direction (action equals reaction - Newton's 3rd Law). It doesn't matter what the rocket expels.

In this case, the student on the skateboard is the rocket and the medicine ball is the engine. The reacting movement (student moving backwards) is based on the acceleration of the initial medicine ball throw (acceleration = force of the throw divided by the mass of the medicine ball - Newton's 2nd Law). You could also include Newton's 2nd Law if you wish to add to the complexity of the demonstration.

To further emphasize Newton's 3rd Law, I allow the group to play catch with the medicine ball. Every throw and catch moves the student on the skateboard backwards, showing every action has an equal and opposite reaction. Be careful - I once had a student complain of bruised ribs after catching an overzealous throw.

*Pulling the 'student learning' from this activity.*

*Staircase of Complexity: Pulling the 'student learning' from this activity.*

# Newton's 3rd Law: Skateboard Activity - Newton's Laws Expo (8 of 9)

Lesson 8 of 12

## Objective: Students will be able to use a skateboard and a large mass to experiment with Newton's 3rd Law.

This lesson is based on California's Middle School Integrated Model of NGSS.

MS-PS2 Motion and Stability: Forces and Interactions

**PE**: MS-PS2-1 - Apply Newton's Third Law to design a solution to a problem involving the motion of two colliding objects.

**DCI**: PS2.A - For any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first, but in opposite directions (Newton's 2nd Law).

**Science and Engineering Practices7: **Engaging in Arguments from Evidence

**Crosscutting Concept: **Cause and Effect

This activity can be used as a stand alone lesson or can be placed with eight other lessons, designed as an exposition to be experienced over three days.

Newton's Laws Expo contains:

- Coin Activity (1st Law)
- Hammer/Nail Activity (1st Law)
- Greek Waiter Tray (1st Law)
- Penny on a Coat Hanger (1st Law)
- Ping Pong Ball Activity (2nd Law)
- Balloon Racer (2nd Law)
- Paper Clip Racer (2nd Law)
- Skateboard Activity (3rd Law) (this lesson)
- Newton's Cradle (3rd Law)

I have also developed three demonstrations of Newton's Laws

Demonstrations

In this lesson, students engage in a short (eight minute) activity designed to demonstrate one of Newton's Laws. A student on a skateboard throws a medicine ball, causing the skateboard and the student to move backwards in the opposite direction (**MS-PS2-1**). The harder the student is able to throw the medicine ball, the farther and faster the skateboard and the student will travel in the opposite direction (**PS2.A**). It is the student's responsibility to use evidence recorded during the activity to determine that Newton's 3rd Law is being expressed, showing the equal and opposite relationship between action and reaction forces (**SP7**). Each activity has been carefully chosen to replicate a specific effect (**CCC**).

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#### Set-up

*45 min*

Needed Material

- Skateboard
- Helmet
- Elbow pads
- Knee Pads
- Medicine Ball or old soccer ball filled with sand and duct taped together

**TIP**: Thrift stores are good resources for old skating equipment.

Print out a copy of Station Markers. Tape 'Station 8' marker card down to the desk where you intend students will conduct this activity. Each station marker identifies where the activity will take place and provides directions for completing the activity.

Print out a copy of Newton's Laws Exposition packet for each student. The packet includes directions and questions to answer. If you are performing this lesson as a single activity you will only need to print out Activity 8.

This activity is designed to accompany other Newton's Laws Activities. I run this unit as a three day exposition. Day 1 is reserved for showing the students all of the nine activities. Days 2 and 3 allow for an eight minute rotation. I typically have my students experience five activities (40 minutes) on Day 2 and four activities (32 minutes) on Day 3 followed by a recap of the events.

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#### Student Activity

*8 min*

Newton's Third law will be in effect for this lesson. Newton's Third Law states that for every action there is an equal and opposite reaction.

Students will not know what specific law of motion they will be experimenting with. They have to record what they see, gather evidence, and argue about what law is being manipulated.

Directions

- Choose one person with skateboard experience.
- Put on the helmet, knee pads, elbow pads, and wrist guards.
**Sit**on the skateboard holding the medicine ball.- All members stand around to catch any falls.
- Throw the medicine ball forward.

**Student Work Sample**

#### Resources

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#### Extensions

*45 min*

Newton's Law are expressed in a multitude of ways in the English language because Newton's original text ' Philosophiæ Naturalis Principia Mathematica', often referred to as the 'Principia', was written in Latin (as were all scientific articles in that time) and translated into English. As such, there are many different translations, causing confusion with students.

I teach Newton's Three Laws using this translation:

- An object in motion will reamin in motion and an object at rest will remain at rest - unless acted upon by another force.
- Acceleration is based on force and mass (F=ma).
- For every action there is an equal and opposite reaction.

To assist in teaching Newton's Law before this lesson is taught, I have included three Powerpoint lessons:

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- UNIT 1: First Week of School
- UNIT 2: States of Matter
- UNIT 3: Periodic Table
- UNIT 4: Atomic Structure
- UNIT 5: Chemical Reactions
- UNIT 6: Forces
- UNIT 7: Density and Buoyancy
- UNIT 8: Motion
- UNIT 9: Solutions
- UNIT 10: Earth, Moon, and Sun
- UNIT 11: Solar System
- UNIT 12: Engineering and Design

- LESSON 1: Newton's 1st Law: Coin Activity (Inertia) - Newton's Law Expo (1 of 9)
- LESSON 2: Newton's 1st Law: Hammer, Nails & Inertia - Newton's Law Expo (2 of 9)
- LESSON 3: Newton's 1st Law: Greek Waiter Tray - Newton's Law Expo (3 of 9)
- LESSON 4: Newton's 1st Law: Penny on a Coat Hanger - Newton's Law Expo (4 of 9)
- LESSON 5: Newton's 2nd Law: Ping Pong Ball Activity - Newton's Laws Expo (5 of 9)
- LESSON 6: Newton's 2nd Law: Balloon Racers - Newton's Law Expo (6 of 9)
- LESSON 7: Newton's 2nd Law: Paper Clip Racers - Newton's Law Expo (7 of 9)
- LESSON 8: Newton's 3rd Law: Skateboard Activity - Newton's Laws Expo (8 of 9)
- LESSON 9: Newton's 3rd Law: Newton's Cradle & Expo (9 of 9)
- LESSON 10: Newton's 1st Law Demonstration
- LESSON 11: Newton's 2nd Law Demonstration
- LESSON 12: Newton's 3rd Law Demonstration