An interactive applet and associated web page that show how to construct a 45 degrees angle with a compass and straightedge. The animation can be single-stepped or run as a continuous movie. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that show how to construct a 60 degrees angle with a compass and straightedge. The animation can be single-stepped or run as a continuous movie. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that provide step-by-step instructions on how to construct an equilateral triangle with a given side length using only a compass and straightedge. The animation can be run either continuously like a video, or single stepped to allow classroom discussion and thought between steps. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that provide step-by-step animated instructions on how to construct a line parallel to a given line through a given point off the line. The animation can be run either continuously like a video, or single stepped to allow classroom discussion and thought between steps. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that provide step-by-step animated instructions on how to construct the incenter of a triangle. The animation can be run either continuously like a video, or single stepped to allow classroom discussion and thought between steps. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

This activity describes the construction and use of a pneumatic cannon and free falling target used to teach the concepts of projectile motion in introductory physics.

If there are air leaks in a house, you might expect that their effect would be magnified on a windy day. The wind creates greater air pressure on the windward side of the building and forces air in through the leaks. At the same time, the pressure on the other side of the building is lowered, pulling air out through leaks. This model has a fan blowing against a building. Air motion is shown with arrows. Open and close the "windows" in the building and observe the results.

Convection refers to transfer of heat by a fluid material (such as air or water) moving from one place to another. The convection is forced if the fluid motion is caused by a fan or a pump while natural convection is the result of density differences.

Conduction of heat refers to the transfer of heat through a solid. Convection refers to the transfer of heat by a fluid material (such as air or water) moving from one place to another. Warm air is less dense than cold air, so it rises and cold air sinks. This is called natural convection. Air is constantly circulating indoors and outdoors, moving heat from one place to another. With this model you can compare how conduction and convection transfer heat.

The convection of heat in air happens naturally because warmer air is less dense and rises, causing air circulation in many situations. But not always! Air can stratify, with warmer air up high and cooler air down low. With this model you can explore how convection works if the heat source is near the ceiling of a room. You can also compare it to conduction in the same setting.

Air circulates quickly and easily if there are temperature differences to drive its motion. This may be desirable in a room, but in insulated walls and ceilings air circulation is a problem, since it transfers heat. Explore the effect of multiple barriers on the amount of convection and apply this to how insulation should be designed.

Most buildings have leaky places where air can enter or escape -- around windows, ceiling openings like pipes, wires or chimneys, and construction joints such as where the wall meets the floor or the floor rests on the foundation. The size and location of these leaks strongly affects the heating and cooling load. Use this model to experiment with wall and roof leaks in a house with a heater where the air can circulate freely.

Explore how potential energy created by particles of varying charge is converted to thermal energy.

This lesson is designed to meet the following learning objectives:
1. Formulate an argument
2. Learn how to anticipate and respond to objections

A set of eight photographs compiled into a series of slides explain how urban areas are facing challenges in keeping both their infrastructure and their residents cool as global temperatures rise. Chicago is tackling that problem with a green design makeover. This report is part of PBS's Coping with Climate Change series and could challenge students to consider engineering designs to help their own cities be greener.

This demonstration uses sulfuric acid and crushed copper ore (malachite) to produce a solution of copper sulfate and carbonic acid in a beaker. When a freshly sanded nail is dropped into the copper sulfate solution, native copper precipitates onto the nail. The process is similar to that of heap leaching at a copper mine. The entire set-up can be placed on a wheeled cart and completed in less than 15 minutes in class. Students enjoy seeing the copper crystals form on the nail, and the experiment provides the basis for many avenues of discussion, from chemical reactions and mineral formation to problems with mine tailings and acid mine drainage.

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An interactive applet and associated web page that provide step-by-step instructions on how to copy a line segment using only a compass and straightedge. The animation can be run either continuously like a video, or single stepped to allow classroom discussion and thought between steps. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that provide step-by-step instructions on how to divide a line segment into any number of equal parts, using only a compass and straightedge. The applet starts with a given line segment and ends with that segment divided into n parts. In the applet n=5, but the construction works for any n. The animation can be run either continuously like a video, or single stepped to allow classroom discussion and thought between steps. The text on the page has printable step-by-step instructions. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

Corona-land is a simulator that visualizes how a virus like the coronavirus spreads and what we can do to contain it. This is an exploration and learning tool and is not a professional tool intended at decision making, planning or forecasting.

Designed and developed by Thomas Riisgaard Hansen, Kite Invent og Aarhus Universitet
Graphic Assistance by Tue Pico, Javira

Visualize the electrostatic force that two charges exert on each other. Observe how changing the sign and magnitude of the charges and the distance between them affects the electrostatic force.