Reflection: Developing a Conceptual Understanding Newton's 2nd Law: Ping Pong Ball Activity  Newton's Laws Expo (5 of 9)  Section 3: Student Activity
The best strategy for teaching Newton's 2nd Law, that I have found, is to focus on the relationship between force(F), mass(M), and acceleration(a); which can be expressed as the formula F=ma or force(F) equals mass(m) times acceleration(a). In other words, the force placed on an object is based on the objects mass and at what rate of speed it is traveling.
In a prior lesson Newton's 2nd Law Demonstration the students build a variable strip that allows them to manipulate the three variables contained within Newton's 2nd Law.
To build, cut three holes (about the size of a quarter) at each end and in the middle of a sentence strip. Label each hole as mass, force, and acceleration (in that order). A student can then insert their finger into the hole representing the variable they wish to remain constant. By placing their finger in the other hole they can raise or lower that value and the third variable reacts accordingly (either high or lower). So if force remains constant, an increase in acceleration requires a decrease in mass. In Newton's 2nd Law Demonstration each student must present their variable strip to their elbow partner and explain how the three variables interact.
Newton's 2nd Law: Ping Pong Ball Activity  Newton's Laws Expo (5 of 9)
Lesson 5 of 12
Objective: Students will be able to test Newton's 2nd Law of motion using ping pong balls and golf balls.
This lesson is based on California's Middle School Integrated Model of NGSS.
MSPS2 Motion and Stability: Forces and Interactions
PE: MSPS22  Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.
DCI: PS2.A  The motion of an object is determined by the sum of the forces acting on it; If the total force the object is not zero, its motion will change (Newton's 1st Law). The greater the mass of the object the greater the force needed to achieve that same change in motion. For any given object, a larger force causes a larger change in motion (Newton's 2nd Law).
Science and Engineering Practices (7) Engaging in Arguments from Evidence
Crosscutting Concept (2) 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) (this lesson)
 Balloon Racer (2nd Law)
 Paper Clip Racer (2nd Law)
 Skateboard Activity (3rd Law)
 Newton's Cradle (3rd Law)
I have also developed three demonstrations of Newton's Laws
Demonstrations
With this lesson, students engage in a short (eight minute) activity designed to demonstrate one of Newton's Laws. The acceleration of a ping pong ball will be compared to the acceleration of a golf ball when a constant force is applied (MSPS22). The large mass (golf ball) should show a lower acceleration then the small mass (ping pong ball) (PS2.A). It will be the student's responsibility to use evidence recorded during the activity to determine that Newton's 2nd Law is being expressed, show the connection between force (F), mass (m), and acceleration (a) (SP7). Each activity has been carefully chosen to replicate a specific effect (CCC).
Setup
Needed Material
 Wooden rulers
 Ping Pong balls
 Golf balls
Print out a copy of Station Markers. Tape 'Station 5' 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 5.
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 all the students 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.
Resources (2)
Student Activity
Newton's Second Law will be in effect for this lesson. Newton's Second Law states that acceleration (a) is based upon force (F) applied to the object and the mass (m) of the object. A change in force or mass will change the object's acceleration. This law can be summed by the formula F=ma (Force = mass X acceleration).
Students will not know what specific law of motion they will be experimenting with. They will have to record what they see, gather evidence and use this to make an informed decision as to which law this activity address. Then they use argumentation, based upon their evidence, to discuss what law is being manipulated.
Directions
There are two sets of directions to experience Newton's 2nd Law: 1) Constant Force, and 2) Constant Acceleration.
Constant Force 1) Place a pingpong ball in front of the wooden ruler. 2) Carefully bend the ruler back and release it. 3) Record your observations 4) Place a golf ball in front of the wooden ruler. 5) Carefully bend the ruler back and release it. Be sure to bend the ruler back to the same spot (force needs to be constant). 6) Record your observations.

Constant Acceleration 1) Place a pingpong ball in front of the wooden ruler. 2) Carefully bend the ruler back and release it. 3) Record your observations 4) Place a golf ball in front of the wooden ruler. 5) Carefully bend the ruler back and release it. Be sure to bend the ruler back to achieve the same acceleration as the pingpong ball (acceleration needs to be constant). 6) Record your observations.

Student Work Sample
Resources (1)
Resources (1)
Resources
Extensions
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 with this translations.
 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 assit in teaching Newton's Law before this lesson is taught, I have included three Powerpoint lessons:
Resources (3)
Similar Lessons
The Wagon and The Ball
Environment: Urban
Environment: Rural
FloataBoat: Introduction to Scientific Inquiry and Design (Part 2/2)
Environment: Suburban
 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