An interactive applet and associated web page that demonstrate the central angle of a circle - the angle subtended at the center by two points ion the circle. The applet presents a circle with two points on it that can be dragged. The central angle is shown changing as you drag. 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.

At its core, the LEGO MINDSTORMS(TM) NXT product provides a programmable microprocessor. Students use the NXT processor to simulate an experiment involving thousands of uniformly random points placed within a unit square. Using the underlying geometry of the experimental model, as well as the geometric definition of the constant π (pi), students form an empirical ratio of areas to estimate a numerical value of π. Although typically used for numerical integration of irregular shapes, in this activity, students use a Monte Carlo simulation to estimate a common but rather complex analytical form the numerical value of the most famous irrational number, π.

The same object can look completely different depending on which coordinate system is used.

This collection of videos, animations and documents comes from the NCSSM AP chemistry online course. Chapter nine provides practice and demonstrations related to chemical bonding and geometry.

An interactive applet and associated web page that demonstrate a chord of a circle. The applet shows a circle and two draggable points on its periphery, with the chord drawn between them. A command button turns on the perpendicular bisector of the chord. As you drag the chord about, you can see that the perpendicular bisector always passes through the center of the circle. 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 task is primarily about volume and surface area, although it also gives students an early look at converting between measurements in scale models and the real objects they correspond to.

An interactive applet and associated web page defining a circle. The applet shows a circle where the user can drag the center and a point on the circle. The radius line supports the definition that all points on the circle are a fixed distance from the center. The web page has the definitions of all the circle-related objects, such as diameter, chord etc, with links for each. 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 task shows that the three perpendicular bisectors of the sides of a triangle all meet in a point, using the characterization of the perpendicular bisector of a line segment as the set of points equidistant from the two ends of the segment. The point so constructed is called the circumcenter of the triangle.

An interactive applet and associated web page that show the properties of a circumcircle of a polygon. The applet shows a regular polygon where the user can drag the vertices to reshape it and alter the number of sides. As the polygon is being varied, the circumcircle is shown, passing through all vertices. The text describes two ways to calculate the radius of the circumcircle, depending on what you are given to start. 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 circumference of a circle. The applet shows a circle with a radius line. The radius endpoints are draggable and the circle is resized accordingly. The formula relating radius to circumference is updated continually as you drag. Introduces the idea of Pi. The formula can be hidden for class discussion and estimation. See also the entries for circumference and diameter. See also entries for radius and diameter. 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 the definition and properties of the bounding box of a polygon or set of points. The bounding box is used in other entries to find area using the so-called box method. The grid, coordinates and calculations can be turned on and off for class problem solving. The applet can be printed in the state it appears on the screen to make handouts. The web page has a full definition of a bounding box when the coordinates of the points defining it are known, and has links to other pages relating to coordinate geometry and a worked example. 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 short video and interactive assessment activity is designed to teach third graders about classifying all types of triangles by lengths of sides.

This short video and interactive assessment activity is designed to teach third graders an overview of triangle classifications.

This short video and interactive assessment activity is designed to teach third graders about classifying triangles based on equal sides.

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Accuracy of measurement in navigation depends very much on the situation. If a sailor's target is an island 200 km wide, sailing off center by 10 or 20 km is not a major problem. But, if the island were only 1 km wide, it would be missed if off just the smallest bit. Many of the measurements made while navigating involve angles, and a small error in the angle can translate to a much larger error in position when traveling long distances.

With a focus on experiential learning, Brock University students worked collaboratively with Niagara Catholic District School Board teachers to develop engaging, coding-based activities for students that were explicitly or implicitly about mathematics. For more information, read the News Article from Brock University.

Teams first explored some resources developed by Dr. George Gadanidis, which led them to further develop 4 CT-based math tasks, which summaries you can access below.

1. Probability & Scratch
2. Exploring Geometry & Patterning with Coding
3. Creating a T-Shaped Puzzle with CNC
4. DASHing the way to Scratch

An interactive applet and associated web page that demonstrate the concept of collinear points. Four draggable points are shown. Dragging any one of them will cause the others to move so they are always collinear. A button controls the line that can be drawn through them. 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 must calculate the volume of a cone in this real world task.

An interactive applet and associated web page that demonstrate the concept of complementary angles (angles that add to 90 degrees). The applet shows two angles. You can drag the endpoints of each angle and the other angle changes so that they always add to 90 degrees. They are drawn in such a way that it is visually obvious that together they form a right angle, although they are separate on the page. The angle measure readouts can be turned off for class 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.