Step by Step Science Posts 500th YouTube Video!

The first videos in January of 2010 were on radioactivity, fission, and fusion. The 500th video completes a series on simple machines. In between, Step by Step Science has explained physics, chemistry and math to students of all ages around the world in short videos that guide them through the concepts, equations and formulas that they need to know to succeed in school.

Here are some of our most popular playlists, with selected videos and user comments.

Optics: Ray Diagrams, Reflection, Refraction, Thin Lens Equation: Topics include reflection, refraction, index of refraction, total internal reflection and the thin lens equation. This is the video series that made me realise it’s best to explain how to solve physics problems in a step by step manner. For lenses and mirrors there are about twenty different ray diagrams that students need to be able to draw. It might sound like a lot, but really they are all drawn the same way. The first ray enters the lens or mirror parallel to the principal axis and exits through the focal point and then the second ray is just the opposite — it enters through the focal point and exits parallel to the principal axis. If you can master those two steps then you are 90% there.

this is amazing! thank you for doing this!!! it really helped me with my test!! i received an A+!!!!!!!!!!!!!!!!!!

Chemical Reactions and Stoichiometry: Covers the five types of chemical reactions and stoichiometry. The beauty of video is that students can see the wonder of chemical reactions from any place in the world. Each of these videos contains a detailed explanation of the chemical reaction and one or more demonstrations showing the type of reaction taking place. Bringing the chemical reactions to life makes a powerful impression on students.

ALL OF YOUR CHEMICAL REACTION VIDEOS HAVE BEEN SO HELPFUL!!! I am not exaggerating, you have saved my life.

RC and RL Circuit Analysis: All you need to know about resistors in combination with capacitors and inductors in DC circuits. How to calculate voltage, current, capacitance and inductance. This is a very confusing topic for many students. Therefore, it is important to start at the beginning: What is meant by time equals zero seconds? When is time equal to zero seconds? From there, build up the students’ understanding, one step at a time.

this 7 min video answered more questions than all the others combined – such a well done video !! 🙂

Linear Equations: Step by step approach to writing, graphing and solving linear equations. I made this series a few years ago when I was teaching math to eighth graders. Now they have become some of my most popular videos. I am sure it is because I clearly go through the steps students must execute to solve problems for linear equations. Students want to learn, they just need someone to show them how to do it step by step.

your explanation is awesome! I never understood this topic until I saw your simplest step by step video. Thank you.

These playlists and videos have one thing in common: they break down problems and concepts into their most basic components and build student understanding through step by step explanations. Nearly all videos are under 15 minutes and fill gaps for students who may have missed class or are missing content from their teachers or textbooks.

Thank you for your support and all the great comments over the past years. I am looking forward to making the next 500 videos! And we will see you in the next video.

Sink or Swim

Do you need a great activity for teaching your kids or students about the scientific process? The Sink or Swim experiment is a fun way to help students develop skills in measurement, calculation and estimation. They will also learn about the concept of density while determining whether an object will sink or float.

Wikimedia Commons

Density is defined as the amount of mass per unit of volume, i.e. the grams of mass per cubic centimeter of volume. Water has a density of 1.00 g/cm3. Objects that have a density greater than 1.00 g/cmwill sink, while objects that have a density less than 1.00 g/cmwill float.

The goal is to get a can to sit as low as possible in a container of water without sinking. Besides the container of water and some empty cans, all you need are a scale, some sand, and a ruler. Our Making YOU The Scientist video walks you through the steps to determine how much sand to add to the can to get the maximum possible density that will keep the can afloat. First you’ll need to determine the volume of the can and then the combined mass of the can and sand that is needed to get the selected density. Watch the video to get all the details on how to do the measurements and calculations.

You can find the instructions for this Sink or Swim experiment, along with some sample density calculation problems, in my TpT store. Turn this experiment into a challenge activity and give a prize to the person whose can floats lowest in the water.

Density measurements are used in the construction industry for calculating the distribution of weight for buildings, vessels, and other objects. The next time you’re planning a river trip, make sure you choose a raft or boat with the proper density to keep you afloat!

Salty Science

Did you know that you can make ice cream in a bag with just ice, salt and a few other ingredients? Salt is the ingredient that lets you chill the mixture to the right temperature to make a tasty frozen treat. The salt acts to lower the temperature at which a solution freezes. This is known as freezing point depression. You may not be familiar with the term, but you are probably aware that salt is used on icy roads to keep them from freezing in the winter, just like antifreeze is used in cars to prevent radiators from freezing or overheating in extreme weather.

All you need is ice, salt, sugar, and milk or cream to make ice cream in a bag. Spice it up by adding your favourite flavours. Ours was delicious!

Our newest Making YOU the Scientist activity explores the concepts of freezing point depression and phase changes. The freezing point of water is zero degrees celsius. In the first part of the activity you will lower the freezing point of water to below zero degrees celsius using ordinary table salt (sodium chloride). The salt will depress or lower the freezing point of the water. 

Freezing point depression is a colligative property of water. Colligative properties are the physical changes that result when a solute is added to a solvent. This experiment uses water as the solvent and salt as the solute. You could also use alcohol or other types of salts to lower the freezing point. Colligative properties do not depend on the type of solute that is added to the solvent, but on how many particles of the solute are added to it.

In the second part of the experiment, you will further explore the phase changes that take place when room temperature water is added to your salty ice water mixture. Phase changes occur when energy is added to or removed from a substance. When energy is removed from a substance, the particles of the substance begin to move more slowly and when the freezing point is reached they will stop moving and the substance will change from a liquid to a solid.

Watch the video to see what happened when we placed a test tube with tap water into our beaker of salty ice water. To further explore the concepts of freezing point depression and phase changes, check out my full write-up for this experiment in my TpT store.

Work, Energy and the Power of Rubberbands

What are work and energy and how are these important concepts related to each other? This is what I ask my eigth grade students at the start of our unit on conservation of energy.

Work is a hard term to define in physics. While sitting quietly and “working” at their desks, students often comment that they have too much “work” to do or that something is a lot of “work”. But unless you are just sitting there pushing your iPad back and forth across the tabletop, chances are you are doing little if no real work. That is because in order to do work in physics a force must be applied to an object to move it through a distance. It doesn’t matter how hard you push on something — if the object does not move, then no work is done.

A great way for students to explore the relationship between work and energy is to have them build cars that are powered only by rubberbands. Stretching a rubberband stores energy in it that can later be used to power the car. Besides the basic physics concepts, students must also consider the design and technology elements of their cars. To receive full credit in my class, their car should travel in a straight line for at least 10 meters.

After students build their cars it’s race time. Who can cover 10 meters in the shortest amount of time? To get things started, the rubberbands are wound around the rear axel of each car. In doing so a force is applied over a distance and potential energy is stored in the rubberband. This gives the rubberband the potential to do work. Hold it tight, place it on the floor and away it goes, gaining velocity as potential energy is converted into kinetic energy.  

Popsicle stick catapults and spinning cup helicopters are other great activities that help students learn about how energy can be stored in elastic materials and then put to work. Work and energy, you can’t have one without the other.

To learn more about this topic, check out my full energy, work and power playlist.

The Power of Electromagnets

Need to sort through all that junk in your basement? Why not build an electromagnet to do the job for you.  An electromagnet is a special type of magnet that is created when a current flows through a coil of wire. These magnets separate materials that contain iron from those that don’t.

You can build your own electromagnet by watching a demonstration in our latest Making You the Scientist video. A related lab activity from our TpT store helps students investigate the relationship between the number of times a wire is wound around a metal bolt and the strength of the electromagnet. The activity contains detailed instructions and a guide to  collecting data, constructing a graph and interpreting the data.

 The main advantage of an electromagnet over a permanent magnet is that the strength of the magnetic field can be adjusted by controlling the amount of electric current. Electromagnets are widely used as components of other electrical devices, such as motors, generators, electromechanical solenoids, relays, loudspeakers, hard disks, MRI machines, scientific instruments, and magnetic separation equipment. They are also commonly used for picking up and moving heavy iron objects such as scrap iron and steel.

Even if you don’t have a pressing need for an electromagnet in your home, the process of building and testing one is a great way to experience the scientific process, and will make You the scientist.

Making YOU the Scientist

Students should develop a love of science by doing science. That’s why Step by Step Science is excited to launch a new series of videos with live experiments and demonstrations that can be done from home, classrooms, or just about anywhere. These are fun activities that are easy to set up and will cover basic aspects of chemistry and physics. Most require materials that you can find in your home or at your local grocery store.

The Density of Liquids Experiment uses water, salt and food colouring to demonstrate what happens when liquids of different densities interact with each other. Find out why the liquids sometimes combine to form a mixture and other times remain separate in this easy, hands on activity. Kids of all ages love this experiment.

All the experiments in this series will be covered in one of my YouTube videos and paired with written instructions and worksheets that guide students through the scientific procedure. You can get the written materials for the Density of Liquids experiment at no cost by following this link to my Teachers Pay Teachers store. And below you can watch the video with the experiment.

Stay tuned for more hands-on experiments that give students the chance to become scientists.

Quizizz, Kahoot! or Something Else? Making Assessments Fun

Teachers often look for new ways to incorporate digital technologies into their classrooms. One way to do this is through gamification, which means adapting elements of game-play to learning activities. Gamification has not only become very popular, it is also a proven method of enhancing student knowledge. According to Matthew Lynch with The Tech Edvocate, though many subjects can be gamified, games can be particularly helpful when teaching students science-based lessons

Before I was even familiar with the term gamification, I was playing Jeopardy with my students to review material before chapter tests. Students loved competing against each other to come up with the right question in response to the ‘answer’ clues on the Jeopardy board. Members of the winning team always received some chocolate or another type of goody. 


Two of the most popular gamification sites are Kahoot! and Quizizz. Both use a colourful format and music to create a high energy, fun learning environment. Both offer a variety of question types, make it easy to create questions, and allow you to import images and change the time allotted for answering questions. Both also award students more points the faster they answer the questions.

The biggest difference is that in Kahoot the questions and answer choices are projected at the front of the classroom, students choose the answers on their devices, and all students answer the same question at the same time. The advantage to this approach is that after each question the teacher has the option of inserting a teaching moment, a review of the question to clarify how to derive the correct answer. 

In Quizizz the questions and answer choices are shown on the students‘ devices and although the questions are also timed, students answer the questions at their own pace. Questions can be randomised so that adjacent students do not have the same question at the same time. The Quizizz user interface has more of a “game show” feel with a constantly changing leader board, player icons that can be personalised, silly memes between questions and power ups that students earn after answering questions correctly. These include the popular 50-50 that removes two incorrect answer choices.

Both assessment apps are fun in their own way. I find that younger students prefer Quizizz with its “corny” features and older students like Kahoot with its more “serious” learning environment. The standard music in Kahoot drives me crazy though.

These fast-paced, high-energy games do not offer the best learning environment for everyone. Students who like to work in a slower, less competitive fashion may enjoy something along the lines of pixel art challenges. A popular Teachers Pay Teachers Store, One for the Books, offers a variety of pixel art challenge options. There is also a free ten minute pixel art challenge for teachers so you can familiarize yourself with how they work. Kesler Science, also on Teachers Pay Teachers, has escape room challenges for a variety of middle and high school science subjects.

Bringing game-play into your teaching is a fun way to engage and motivate students. If you have any great game ideas for teaching science or other subjects, please post a comment below.

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.