Here’s a new “spin” on an old toy. In this modern adaptation of a classic toy—the spool racer—a plastic water bottle is propelled by energy stored in a wound-up rubber band.

Students examine how different balls react when colliding with different surfaces, giving plenty of opportunity for them to see the difference between elastic and inelastic collisions, learn how to calculate momentum, and understand the principle of conservation of momentum.

In this activity, students examine how different balls react when colliding with different surfaces. Also, they will have plenty of opportunity to learn how to calculate momentum and understand the principle of conservation of momentum.

David shows how to use conservation of momentum for a situation where two objects bounce off of each other. Created by David SantoPietro.

Watch water boil at room temperature. The temperature at which water boils depends on pressure. You can demonstrate this by dramatically lowering the pressure on a water-filled plastic syringe at room temperature.

Sal explains how to draw free body diagrams when forces are applied at an angle. How to find horizontal and vertical components of an angled force using trigonometry.

In this activity, learners observe as soap bubbles float on a cushion of carbon dioxide gas. Learners blow bubbles into an aquarium filled with a slab of dry ice. Learners will be amazed as the bubbles hover on the denser layer of carbon dioxide gas, then begin to expand and sink before freezing on the dry ice. Use this activity to discuss sublimation, density, and osmosis as well as principles of buoyancy, semipermeability, and interference.

Create giant bubbles! Bubbles are fascinating. What gives them their shape? What makes them break or last? What causes the colors and patterns in the soap film, and why do they change?

Students work in groups to create soap bubbles on a smooth surface, recording their observations from which they formulate theories to explain what they see (color swirls on the bubble surfaces caused by refraction). Then they apply this theory to thin films in general, including porous films used in biosensors, listing factors that could change the color(s) that become visible to the naked eye, and learn how those factors can be manipulated to give information on gene detection. Finally (by experimentation or video), students see what happens when water is dropped onto the surface of a Bragg mirror.

Whether you want to light up a front step or a bathroom, it helps to have a light come on automatically when darkness falls. For this maker challenge, students create their own night-lights using Arduino microcontrollers, photocells and (supplied) code to sense light levels and turn on/off LEDs as they specify. As they build, test, and control these night-lights, they learn about voltage divider circuits and then experience the fundamental power of microcontrollers—controlling outputs (LEDs) based on sensor (photocell) input readings and if/then/else commands. Then they are challenged to personalize (and complicate) their night-lights—such as by using delays to change the LED blinking rate to reflect the amount of ambient light, or use many LEDs and several if/else statements with ranges to create a light meter. The possibilities are unlimited!

Students are challenged to design their own small-sized prototype light sculptures to light up a hypothetical courtyard. To accomplish this, they use Arduino microcontrollers as the “brains” of the projects and control light displays composed of numerous (3+) light-emitting diodes (LEDs). With this challenge, students further their learning of Arduino fundamentals by exploring one important microcontroller capability—the control of external circuits. The Arduino microcontroller is a powerful yet easy-to-learn platform for learning computer programing and electronics. LEDs provide immediate visual success/failure feedback, and the unlimited variety of possible results are dazzling!

Students build their own small-scale model roller coasters using pipe insulation and marbles, and then analyze them using physics principles learned in the associated lesson. They examine conversions between kinetic and potential energy and frictional effects to design roller coasters that are completely driven by gravity. A class competition using different marbles types to represent different passenger loads determines the most innovative and successful roller coasters.

Students create and decorate their own spectrographs using simple materials and holographic diffraction gratings. A holographic diffraction grating acts like a prism, showing the visual components of light. After building the spectrographs, students observe the spectra of different light sources as homework.

Students design and construct electromagnets that must pick up 10 staples. They begin with only minimal guidance, and after the basic concept is understood, are informed of the properties that affect the strength of that magnet. They conclude by designing their own electromagnets to complete the challenge of separating scrap steel from scrap aluminum for recycling, and share it with the class.

In this video we show you how to build a simple motor. Created by Karl Wendt.

Students conduct a simple experiment to see how the water level changes in a beaker when a lump of clay sinks in the water and when the same lump of clay is shaped into a bowl that floats in the water. They notice that the floating clay displaces more water than the sinking clay does, perhaps a surprising result. Then they determine the mass of water that is displaced when the clay floats in the water. A comparison of this mass to the mass of the clay itself reveals that they are approximately the same.

A couple of problems involving Archimedes' principle and buoyant forces. Created by Sal Khan.

Turn an old CD into a spectroscope to analyze light—you may be surprised by what you see. Try pointing your CD spectroscope at the fluorescent light in your room, sunlit clouds in the sky, even your friend’s colored shirt to reveal the wavelengths of light that mix together to create the color you see!

Calculating the dot and cross products when vectors are presented in their x, y, and z (or i, j, and k) components. Created by Sal Khan.

Students apply their knowledge of linear regression and design to solve a real-world challenge to create a better packing solution for shipping cell phones. They use different materials, such as cardboard, fabric, plastic, and rubber bands to create new “composite material” packaging containers. Teams each create four prototypes made of the same materials and constructed in the same way, with the only difference being their weights, so each one is fabricated with a different amount of material. They test the three heavier prototype packages by dropping them from different heights to see how well they protect a piece of glass inside (similar in size to iPhone 6). Then students use linear regression to predict from what height they can drop the fourth/final prototype of known mass without the “phone” breaking. Success is not breaking the glass but not underestimating the height by too much either, which means using math to accurately predict the optimum drop height.