Students are challenged to design a method for separating steel from aluminum based on magnetic properties as is frequently done in recycling operations. To complicate the challenge, the magnet used to separate the steel must be able to be switched off to allow for the recollection of the steel. Students must ultimately design, test, and present an effective electromagnet.

As a continuation of the theme of potential and kinetic energy, this lesson introduces the concepts of momentum, elastic and inelastic collisions. Many sports and games, such as baseball and ping-pong, illustrate the ideas of momentum and collisions. Students explore these concepts by bouncing assorted balls on different surfaces and calculating the momentum for each ball.

In this optics activity, learners discover that not all shadows are black. Learners explore human color perception by using colored lights to make additive color mixtures. With three colored lights, learners can make shadows of seven different colors. They can also explore how to make shadows of individual colors, including black. Use this activity demonstrate how receptors in the retina of the eye work to see color.

Charge can flow through some materials, but not others. Created by David SantoPietro.

Definition of period and frequency for an object moving in a circle. Connecting period and frequency to the magnitude of the angular velocity.

How angular momentum is conserved within a system when there is no external torque.

Charge can't be created, and it can't be destroyed. Created by David SantoPietro.

A conservative force exists when the work done by that force on an object is independent of the object's path. Instead, the work done by a conservative force depends only on the end points of the motion. An example of a conservative force is gravity. Created by David SantoPietro.

In this video David explains what constructive and destructive interference means as well as how path length differences and pi shifts affect the interference. Created by David SantoPietro.

Bluetooth is everywhere—from smartphones to computers to cars. Even though students are exposed to this technology, many are not aware of how they can use it themselves to wirelessly control their own creative projects! For this challenge, students build on what they learned during a previous Arduino maker challenge, Make and Control a Servo Arm with Your Computer, and learn how to control a servo with an Android phone (iPhones do not work with the components used in this challenge). By the end of the exercise, expect students to be wirelessly controlling a servo with a simple phone application!

In this activity, learners make their own heat waves in an aquarium. Warmer water rising through cooler water creates turbulence effects that bend light, allowing you to project swirling shadows onto a screen. Use this demonstration to show convection currents in water as well as light refraction in a simple, visually appealing way.

Students teams design and build shoe prototypes that convert between high heels and athletic shoes. They apply their knowledge about the mechanics of walking and running as well as shoe design (as learned in the associated lesson) to design a multifunctional shoe that is both fashionable and functional.

The phenomenon is thermal expansion of copper. This demonstration allows an observer to see the effect of heating (and cooling) a copper tube. When heated, the copper tube lengthens and thickens. When cooled, the tube shrinks. The lengthening of the rod rotates a toothpick with an attached flag to make the expansion visible and measurable.

Sal explains the fundamental force that causes charged particles to attract or repel each other.

The students discover the basics of heat transfer in this activity by constructing a constant pressure calorimeter to determine the heat of solution of potassium chloride in water. They first predict the amount of heat consumed by the reaction using analytical techniques. Then they calculate the specific heat of water using tabulated data, and use this information to predict the temperature change. Next, the students will design and build a calorimeter and then determine its specific heat. After determining the predicted heat lost to the device, students will test the heat of solution. The heat given off by the reaction can be calculated from the change in temperature of the water using an equation of heat transfer. They will compare this with the value they predicted with their calculations, and then finish by discussing the error and its sources, and identifying how to improve their design to minimize these errors.

Students learn about the physical force of linear momentum movement in a straight line by investigating collisions. They learn an equation that engineers use to describe momentum. Students also investigate the psychological phenomenon of momentum; they see how the "big mo" of the bandwagon effect contributes to the development of fads and manias, and how modern technology and mass media accelerate and intensify the effect.