Teaching Newton’s Laws of Motion

Along with Albert Einstein, Sir Isaac Newton is probably one of the best known scientists in the world. Everyone knows his name, but few people can state his three laws of motion and even fewer can explain their application in the real world. Did you know Newton first presented his three laws of motion in 1686?

Many of the principles involved in teaching Newton’s laws of motion are abstract in nature and deal with concepts that students can not directly observe. Students come to physics class with various preconceived notions about the laws that govern the motion of objects in our everyday world. And many of these notions are incorrect. To overcome misconceptions, teachers need to incorporate a variety of teaching methodologies into their instruction. These should include physics demonstrations, traditional instruction such as lectures, and the use of practice exercises and student centered activities such as labs, practical work and discussions.

I always begin my unit on Newton’s laws with the classic demonstration of dropping two objects with different masses from the same height. I ask the students which object will hit the ground first and require them to write down their answer and explain their choice. This forces each student to think about their selection. Next, I stand on one of the classroom tables, hold the objects as close to the ceiling as possible and prepare to drop them…3, 2, 1….!! Having captured everyone’s attention I stop just before releasing the objects, jump off the table and tell the students that we should first discuss the forces that are acting on the objects. Now I can introduce the concepts: What is a force?, What is gravity?, What is the difference between mass and weight? Before finally dropping the objects, we discuss the possible results and I give everyone a chance to revise original choices.

In the following classes we move on to further instructional material that I’ve developed, including online labs using PhET Interactive Simulations. These simulations require no set up, provide accurate and repeatable results, and are designed based on research into how students learn. Students also learn how to perform quantitive analyses of the motion of objects, including the use of Newton’s second law of motion: F = m • a. All my PhET lab activities, along with problem sets and exercises with notes and solutions for a variety of second law scenarios, are available from my Teachers Pay Teachers store.

These activities and exercises are designed for use with the instructional videos on my YouTube channel. Each video provides an in-depth explanation of the concepts covered in the materials. The videos bring the concepts to life, especially for students who are learning from home during the pandemic.

More to Reading a Graph than Meets the Eye

Are you a visual learner, someone who learns best by seeing concepts or ideas? If so, you probably like using pictures, graphs and charts to learn new things. But what about auditory and kinesthetic learners, those who learn better by hearing, doing, and touching? Physical science relies heavily on conceptual images to illustrate concepts like velocity, forces, density, and electric current. Reading a graph can be challenging for some students so it’s important to develop assignments that teach students how to accurately read and interpret visual information.

One of my favorite assignments is to have students compare and interpret the information presented in position and velocity vs. time graphs. In class we spend a significant amount of time first discussing the meaning of the position vs. time graph and then the velocity vs. time graph. Next, I present the assignment and ask my students to describe the motion of the object during each of the time intervals a through n. They should be able to say whether the object is at rest, moving with a constant velocity or accelerating.

Is the object at rest, moving with a constant velocity or accelerating?

If the object is moving with a constant velocity, what is the direction of motion?

If it is accelerating, is it speeding up or slowing down and in which direction?

When given the two different graphs with the same shape, students give me a lot of confused looks and are hesitant about how to begin. Often, they incorrectly jump to the conclusion that because the graphs look the same they mean the same thing. Because students tend to state the first thing that comes to mind, they need to be reminded that it is important to first take a few minutes to think about what information is presented on each graph. In this case, both graphs have time on the x-axis but different information is presented on the y-axes. How does that affect the description of the object’s motion?

Ask your students, “How does the meaning of a horizontal line on the position vs time graph differ from a horizontal line on the velocity vs time graph?” Let them think about it for a few seconds and suddenly a few eyes will brighten as they begin to realize the difference. Now they can move on to the sections of the graph that have positive and negative slopes. Remind them that just because the graphs are on the same page and look the same, they do not present the same information. In fact, the information is quite different and each one needs to be analyzed separately.

This assignment is part of my Kinematics: Velocity vs Time Graphs product in my TpT store. With so much data and visual information to absorb nowadays, graphs and data tables are becoming more and more ubiquitous. This increases the importance of teaching students how to accurately read and understand the data presented to them.

Light Up Your Classroom With The Flame Test Lab

As this year comes to an end and those of us in the Northern Hemisphere approach the darkest time of our endless journey around our humble central star, what better way to light up your classroom than with the brilliant colors of the flame test lab. This activity combines everything that students love: lab work, flames and color. It’s a must for your high school science class.

You can find a full write-up of this lab, including student worksheets and solutions, at my Teachers pay Teachers store. And here’s a link to my Flame Test Colors video.

Just like every person has a unique finger print, the color of light emitted by a metal when heated in a flame is unique to that metal. The flame’s test colors can be seen immediately, they are easy to identify and brilliant in their effect. Every year my students thank me for the chance to do this lab…at least until they remember that there is a lab write-up that they must complete.

In this lab students will try to identity the following six metal salts based on their emission colors:

Name of Metal SaltChemical FormulaFlame Test ColorRepresentative Wavelength
Copper chlorideCuCl2Blue-Green490 nm
Potassium chlorideKClLight Violet410 nm
Lithium chlorideLiClRed-Orange625 nm
Strontium chlorideSrCl2Red650 nm
Sodium chlorideNaClYellow580 nm
Calcium chlorideCaCl2Orange600 nm
Metal Salts and Their Flame Test Colors

This lab is easy to set up and there are no chemicals to mix. The minimal equipment requirements include the metal salts, Bunsen burners, cotton swabs (Q-tips), a few beakers and of course safety goggles. If you don’t have the salts, consider buying the affordable kit from Flinn Scientific.

When the metals are placed in the flame the electrons in each atom absorb energy. This energy is used to move the electrons from their ground state to an excited state. When the electrons move back to a lower energy level they emit the absorbed energy as a particle of light called a photon (see diagram at right). 

Absorption & Emission of Energy

Because every element has a different electron configuration, the energy of the emitted photons will be different and therefore a different color will be emitted by each metal. Using the representative wavelength in the table above and the following equations, students can convert the wavelengths to energies in joules.

c = f ⋅ λ

E = h ⋅ f

Have fun and don’t forget to subscribe to our blog for more upcoming teaching ideas.

Why I Switched to PhET Interactive Simulation Labs

Picture this: It’s Friday afternoon and you have just finished a great week of teaching. Everyone is getting ready to leave, but you are already thinking about Monday. You don’t want to spend the weekend preparing for next week’s classes so you stay until you have the first day of the week planned. Double whammy, Monday is also lab day for 10th grade physics and you will be starting a new unit on electricity and electric circuits. That means organising all of the equipment for your series and parallel resistors lab.

Do you have enough cables?, Where are the power supplies?, Are the bulbs burnt out?, Who took all of your switches and never put them back?, Don’t three of the multimeters need new batteries? Not to mention, because of the coronavirus distance restrictions you can’t really do group labs anymore. That is when you remember that a colleague told you about PhET Simulations from the University of Colorado.

Learning about Energy Conservation with the PhET Skate Park Simulation

PhET simulations are free to everyone and have so many benefits. Students enjoy them because they are visual, intuitive and make connections to real world situations. Most are now developed in HTML5 so they run right in the web browser of your tablet or computer; no apps or programs to download and install. The simulations are designed and developed based on research into how students learn. But what I like most about them is their interactivity. Students can easily manipulate the simulations to see the relationship between the different variables they are exploring. The results are accurate and replicable, allowing students to explore, collect data and draw conclusions from first-hand experiences.

In the Circuit Construction Kit simulations, students can add and remove resistors and directly observe changes in bulb brightness, current and the voltage drop across various circuit elements. In the Pendulum Lab simulation, students manipulate the length, mass, angle of displacement and even the gravity to see what factors affect its period. The Energy Skate Park simulation has several different graphical representations of the skater’s motion allowing the user to make connections between height, velocity, potential energy and kinetic energy. Students can even build their own skate park to further reinforce their observations.

With my PhET simulation teaching materials to guide you and no lab equipment to set up, you can relax and enjoy your weekend. And you’ll be ready to meet your students in class with some engaging new inquiry-based activities.

Step by Step Science Teaching Materials

Finding the right resources to help students learn a topic can be one of the most frustrating and time-consuming parts of a teacher’s job. For every hour of class time, teachers commonly invest many hours to prepare an instructive and engaging session for their students.

I found this material to be extremely helpful and very professional. It’s the complete package, ranging from accurate and brief descriptions and notes to linked videos and a great interactive lab. Thank you!

Teacher, 10th – 12th Grade

Like other teachers, I’ve spent countless hours searching for and creating just the right materials for my science classes. So I was thrilled to discover Teachers Pay Teachers (TpT), a popular marketplace for original educational resources. TpT materials are created by educators, classroom-tested, and available for free or a reasonable price. After finding some great resources to use with my students, I decided to join the platform and offer my own original physics materials.

My TpT resources are designed to accompany the free videos from my Step by Step Science YouTube channel. I combine handouts, worksheets, and presentations in comprehensive sets that reduce preparation time for teachers. You can just download, review and head for the classroom. The combination of teaching materials and videos gives teachers an integrated resource mix that is especially valuable for distance learning. But don’t take my word for it. Try one of my free resources for yourself: Free Sample: Resistors in Series

Many content creators are making educational videos nowadays. Others are making instructional materials. I’m doing both, producing high quality resources that guide students through the world of physics so that they can learn with confidence and be successful in school. Over the next year I’ll be offering more materials on the most important high school physics topics. If you’re a physics teacher, visit the Step by Step Science TpT Store to check out all of my available resources.

Step by Step Science YouTube Channel: How It Began

Every story has a beginning. My YouTube story begins in 2008 when I was teaching science at Bozeman High School in Bozeman, Montana. Too many textbooks had complicated or unclear explanations of the topics I needed to teach. I wanted to break down the concepts into simpler steps, not just for my students but for others who needed help too.

Some of my first video topics were optics, motion graphs, and radioactive decay. These remain some of my most popular videos. Students told me from the start that my explanations helped them to succeed on homework assignments, tests and quizzes. Making science videos became a hobby for me, a hobby driven by positive feedback from students, parents and teachers.

Last year I received my Silver Play Button, YouTube’s reward for reaching 100,00 channel subscribers. These days I’m still passionate about making videos and I’m pairing them with instructional materials that are ready for classroom use. Visit my Step by Step Science YouTube Channel and TeachersPayTeachers Store to access all of my great physics, chemistry and math content.

I started this blog to share my twenty years of experience as a high school science teacher. I’ll be writing about teaching strategies, best practices, classroom activities, and more in the coming months. Please subscribe to my blog and post a comment or get in touch if you have topics you would like me to write about.

Thanks! After hours of reading my textbook until I have a headache and filling a recycling bin with crumpled up papers, I got the concept in 5 minutes thanks to this video! I wish I could like this video once for each incorrect answer in those hours…..

Step by step channel viewer