An interactive applet and associated web page that provide step-by-step instructions on how to construct the orthocenter of a triangle using only a compass and straightedge. The method used involves constructing two altitudes of the triangle, which intersect at the orthocenter. 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.

Students examine consumer choices and fair trade in this excellent grade 7/8 project. Choices are available for I DO, WE DO and YOU DO.

An interactive applet and associated web page that demonstrate the concept of a convex polygon - one where all interior angle are less than 180 degrees. The applet shows an irregular convex polygon initially. The user can drag any vertex, change the number of sides in the range 3..99, and make it regular or irregular. When the polygon is convex, the polygon is so flagged. It is shown that regular polygons are always convex. The goal is to show through experimentation what the concept of convexity really means. 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 describe the concept of the coordinate plane (Cartesian Plane). The applet shows the plane, its axes, origin and related controls. The user can drag a point around and see the coordinates change, and click anywhere to create new points. The origin can be dragged to emphasize or eliminate certain quadrants. The grid, axis pointers and coordinates can be turned on and off. The coordinate display can be turned off to permit class exercises and then turned back on the verify the answers. The applet can be printed as it appears on the screen to make handouts. The web page has a narrative description of the concept. 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 describe the concept of a point in coordinate geometry. The applet show one point initially, but clicking anywhere adds more. As the points are dragged, the coordinates are seen to change. The grid, axis pointers and coordinates can be turned on and off. The coordinate display can be turned off to permit class exercises and then turned back on the verify the answers. The applet can be printed as it appears on the screen to make handouts. The web page has a narrative description of the concept, including the definitions of abscissa, ordinate, coordinates, ordered pair. The 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 demonstrate the concept of coplanar objects - those that lie in the same plane. The applet presents two planes. In one plane there are two rectangles that can be dragged around and which lie in the same plane always. The other is a rectangle that can be dragged but always lies in a plane orthogonal to the first. 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 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.

An interactive applet and associated web page that provide step-by-step instructions on how to copy a given triangle 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 demonstrate the corresponding angles that are formed where a transversal crosses two lines. The applets cycles through the four possible pairs of angles when in animation mode. By dragging the three lines, it can be seen that the angle pairs are congruent only when the lines are parallel. When not in animated mode, there is a button that cycles through each the four pairs of angles. The text on the page discusses the properties of the pairs of corresponding angles both in the parallel and non-parallel cases. 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.

DNA. It's what makes you unique. Unless you have an identical twin, your DNA is different from that of every other person in the world. And that's what makes DNA fingerprinting possible. Experts can use DNA fingerprints for everything from determining a biological mother or father to identifying the suspect of a crime. What, then, is a DNA fingerprint and how is it made? Here, you'll find out by solving a mystery—a crime of sorts. First, you'll create a DNA fingerprint (we'll supply the lab and all necessary materials). Then you'll compare this DNA fingerprint to those of all seven suspects to nab the perpetrator. Ready? Let's get to work!

The following simulated crime scene is designed to test your observation and knowledge. Observe each image and respond only to the questions associated with each image.

An interactive applet and associated web page that demonstrate the properties of a cube. A 3-D cube is shown in the applet which can be interactively manipulated using the mouse. Research has shown that some younger students have difficulty visualizing the parts of a 3D object that are hidden. To help with this, the student can rotate the cube in any axis simply by dragging it with the mouse. It can also be 'exploded' - where a slider gradually separates the faces to reveal the ones behind. The cube can also be made translucent so you see through it to the other side. Applet can be enlarged to full screen size for use with a classroom projector, and printed to make handouts. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet that allows the user to graphically explore the properties of a cubic equation. Specifically, it is designed to foster an intuitive understanding of the effects of changing the 4 coefficients in the function. The applet shows a large graph of a quadratic (ax^3 + bx^2 +cx + d) and has four slider controls, one each for the coefficients a,b,c and d. As the sliders are moved, the graph is redrawn in real time illustrating the effects of these variations. 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.

DASHlink is a virtual laboratory for scientists and engineers to disseminate results and collaborate on research problems in health management technologies for aeronautics systems. Managed by the Integrated Vehicle Health Management project within NASA's Aviation Safety program, the Web site is designed to be a resource for anyone interested in data mining, IVHM, aeronautics and NASA.

Your body is made of cells -- but how does a single cell know to become part of your nose, instead of your toes? The answer is in your body's instruction book: DNA. Joe Hanson compares DNA to detailed manual for building a person out of cells -- with 46 chapters (chromosomes) and hundreds of thousands of pages covering every part of you.

Use the controls to explore this fragment of a much longer DNA strand. Can you find the four different base pairs that DNA is constructed from?

Explore how the code embedded in DNA is translated into a protein. Click Transcribe to zoom into the cell nucleus and see the chromosome unravel to expose the strands of DNA. The DNA separates and an mRNA strand is created by matching complementary nucleotides. Click Translate to watch the mRNA leave the nucleus for the cytoplasm and attach to a ribosome. tRNA molecules bring in amino acids and the amino acids are added in the correct order by matching complementary nucleotides. After translation, inspect the protein to see how the amino acid sequence folded.

Simulate the original experiment that proved that electrons can behave as waves. Watch electrons diffract off a crystal of atoms, interfering with themselves to create peaks and troughs of probability.

A web page and interactive applet illustrating the properties of a decagon (10 sided polygon). The applet shows a decagon where the user can drag any vertex to reshape it. User can see that the interior and exterior angles are constant in a regular decagon, but vary in an irregular version. Controls allow the display or hiding of the diagonals, and triangles within the decagon. The web page lists the properties of a decagon including interior angles, exterior angles, sum of exterior angles, area, number of diagonals and number of internal triangles. Links to pages with generalized properties of all polygons. 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.