An interactive applet and associated web page that demonstrate the concept of ...

An interactive applet and associated web page that demonstrate the concept of 'perpendicular'. The applet presents two intersecting line segments, one initially at right angles to the other. As you drag the end points of the line segments a message and the right-angle mark at the intersection tell if it is currently perpendicular. The goal is to show what a right angle 'looks like'. 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 perpendicular bisector ...

An interactive applet and associated web page that demonstrate the perpendicular bisector of a line segment. The applet shows a fixed line and another moveable one that bisects it. As you drag either end of it, it is seen that only when they are perpendicular to each other is the definition valid. 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 determine ...

An interactive applet and associated web page that show how to determine of one line is perpendicular to another in coordinate geometry. The principle used is that if two lines a re perpendicular to each other the slope of one is the negative reciprocal of the other. The applet shows to lines that the user can move. The slopes are continuously calculated as you drag them, and if the they are parallel they change color. The calculation is shown on screen updated continuously as you drag. The grid, axis pointers and coordinates can be turned on and off. The calculation 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 full description of the concept of perpendicularity, a worked example and has links to other pages relating to coordinate geometry. 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 interactive Flash animation allows students to explore size estimation in one, ...

This interactive Flash animation allows students to explore size estimation in one, two and three dimensions. Multiple levels of difficulty allow for progressive skill improvement. In the simplest level, users estimate the number of small line segments that can fit into a larger line segment. Intermediate and advanced levels offer feature games that explore area of rectangles and circles, and volume of spheres and cubes. Related lesson plans and student guides are available for middle school and high school classroom instruction. <i>Editor's Note: When the linear dimensions of an object change by some factor, its area and volume change disproportionately: area in proportion to the square of the factor and volume in proportion to its cube. This concept is the subject of entrenched misconception among many adults. This game-like simulation allows kids to use spatial reasoning, rather than formulas, to construct geometric sense of area and volume.</i> This is part of a larger collection developed by the Physics Education Technology project (PhET).

"Each student creates parallelograms from square sheets of paper and connects them ...

"Each student creates parallelograms from square sheets of paper and connects them to form an octagon. During the construction, students consider angle measures, segment lengths, and areas in terms of the original square" (from NCTM's Illuminations).

In this math activity, learners observe and sketch cracking patterns in pavement. ...

In this math activity, learners observe and sketch cracking patterns in pavement. Learners use a protractor to measure and label the angles of their sketches and conclude if some angles are more common than others.

In this interactive Flash game learners use their knowledge of coordinates on ...

In this interactive Flash game learners use their knowledge of coordinates on a grid to move Plotter the penguin and avoid trouble. The game includes three levels of difficulty, a story mode, and a choice of five different games to play. Each game provides instruction as well as in-depth help in linked PDF documents.

In this activity, learners create angle-measuring devices--protractors--out of paper. Learners follow a ...

In this activity, learners create angle-measuring devices--protractors--out of paper. Learners follow a series of steps to fold a square sheet of paper into a triangular Pocket Protractor. Learners will practice measuring and identifying the angles of a triangle.

In this activity, learners explore how polarizing sunglasses can help diminish road ...

In this activity, learners explore how polarizing sunglasses can help diminish road glare. By rotating a pair of polarizing sunglass lenses or other polarizing materials, learners will discover that some angles are better at reducing glare than others. Learners observe light from the sky, reflected from a mirror, or reflected from the surface of a pond. Use this activity to introduce learners to principles of light and polarization.

An interactive applet and associated web page that demonstrate polygons. The applet ...

An interactive applet and associated web page that demonstrate polygons. The applet shows a polygon which is initially an irregular convex pentagon. The user can drag any vertex and a message shows if it becomes concave. The user can also alter the number of sides from 3 to 99, the title changing to reflect it's name up to 12 sides. You can also make it regular, dragging a vertex then changes all vertices to maintain it as regular. The web page has many definitions and links to the various forms and orders of polygon. 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.

In this math activity, learners classify polygons according to more than one ...

In this math activity, learners classify polygons according to more than one property at a time. In the context of a game, learners move from a simple description of shapes to an analysis of how properties are related. This lesson guide includes sample steps in the game and extensions.

In this lesson, students classify polygons according to more than one property ...

In this lesson, students classify polygons according to more than one property at a time. As they play the game, they are motivated to examine relationships among geometric properties. Another purpose of the game is to give students a format for using important geometric vocabulary. All game instructions and models for playing pieces are included here.

An interactive applet and associated web page that demonstrate the diagonals of ...

An interactive applet and associated web page that demonstrate the diagonals of a polygon. The applet shows a polygon with the diagonals drawn. The user can drag any vertex, make it regular or irregular, and change the number of sides. The applet continually computes and displays the number of diagonals. The text on the web page has the relevant formulae. 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 that the exterior ...

An interactive applet and associated web page that demonstrate that the exterior angles of a polygon always add to a constant (360 or 720 depending on your point of view). The applet shows a polygon where the user can drag the vertices to reshape it, alter the number of sides, make it convex or concave, regular or irregular. The applet shows the angle summation in real time, demonstrating that it is always constant. It also demonstrates how exterior angles are accounted for in concave polygons, where the exterior angle seems to be inside the figure. These are taken as negative angles and the sum demonstrably remains the same. 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 that the interior ...

An interactive applet and associated web page that demonstrate that the interior angles of a polygon always add to a number related only to the number of sides. The applet shows a polygon where the user can drag the vertices to reshape it, alter the number of sides, make it convex or concave, regular or irregular. The applet shows the angle summation in real time, demonstrating that only the number of sides affects the total. The text on the web page gives the formula for the total of the interior angles. 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.

A page that allows you to print rectangular (cartesian) graph paper. You ...

A page that allows you to print rectangular (cartesian) graph paper. You ca control if grid lines are printed and the position of the origin. By dargging the origin into any corner a single quadrant can be printed. 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 illustrate Pythagoras' Theorem. The ...

An interactive applet and associated web page that illustrate Pythagoras' Theorem. The applet shows a right triangle that can be resized by dragging any vertex. As it is being dragged the formula is continuously recalculated to show that the the theorem always holds for any right triangle. The formula can be turned off to facilitate classroom discussions. 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 demonstrates a graphical proof ...

An interactive applet and associated web page that demonstrates a graphical proof of Pythagoras' Theorem. The applet shows a right triangle that is replicated and then moved around to demonstrate the relationship between the sides. It can can be stepped through slowly to allow classroom discussion, or let to run as a movie. Useful for students who like to see things graphically as opposed to symbolically. 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.

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