An interactive applet and associated web page that demonstrate the exterior angles of a triangle. The applet shows a triangle where the user can drag any vertex to reshape it. The exterior angles are shown and a running calculation shows that no matter how you change the triangle, the exterior angles always add up to 360 degrees An exterior angle is equal to the sum of the opposite 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.

An interactive applet and associated web page that demonstrate the concept of triangle inequality. The applet shows a triangle where the vertices can be dragged to reshape the triangle It shows that no matter what you do, the longest side is always shorter than the sum of the other two. 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 in similar triangles, the ratio of their areas is the square of the ratio of the sides. As you drag one triangle to resize it, it remains similar to another and the ratios of sides and areas is calculated as you drag. One can be seen to be the square of the other at all times. A slight 'snap-to' effect allows easy selection of integer ratios (2:4 etc). 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 reference book project at http://www.mathopenref.com.

An interactive applet and associated web page that illustrate the triangles that can be drawn inside a polygon. The applet has a pentagon with the triangles drawn. The user can change the number of sides, and switch between regular / irregular. The vertices are draggable. The text on the page discusses the uses of these triangles. 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 will create a route for their ozobot to travel using parallel, perpendicular and intersecting lines. They will also create a "trap" to catch the turkey on the route.

Students will create a route for their ozobot to travel using parallel, perpendicular and intersecting lines. They will also create a "trap" to catch the turkey on the route.

Students will create a route for their ozobot to travel using parallel, perpendicular and intersecting lines. They will also create a "trap" to catch a turkey, or other animal, on the route.

In this video segment from Cyberchase, Digit must a make a straight line between the two points and then follow the path created.

Jackie and Matt are looking at the same object along two different lines, in this video segment from Cyberchase.

This task combines two skills from domain G-C: making use of the relationship between a tangent segment to a circle and the radius touching that tangent segment (G-C.2), and computing lengths of circular arcs given the radii and central angles (G-C.5). It also requires students to create additional structure within the given problem, producing and solving a right triangle to compute the required central angles (G-SRT.8).

This short video and interactive assessment activity is designed to teach fourth graders how to, given the perimeter, find the side length and area - squares.

This task presents a context that leads students toward discovery of the formula for calculating the volume of a sphere. Students who are given this task must be familiar with the formula for the volume of a cylinder, the formula for the volume of a cone, and CavalieriŐs principle.

Students in this lesson will learn about, connect and apply the use of area to a real-world problem—creating a planting guide for the garden. Students will determine the square footage of the garden and use this information, along with a planting chart to create their own plan.

This lesson unit is intended to help you assess how well students are able to: recognize and use common 2D representations of 3D objects and identify and use the appropriate formula for finding the circumference of a circle.

This video is meant to be a fun, hands-on session that gets students to think hard about how machines work. It teaches them the connection between the geometry that they study and the kinematics that engineers use -- explaining that kinematics is simply geometry in motion. In this lesson, geometry will be used in a way that students are not used to. Materials necessary for the hands-on activities include two options: pegboard, nails/screws and a small saw; or colored construction paper, thumbtacks and scissors. Some in-class activities for the breaks between the video segments include: exploring the role of geometry in a slider-crank mechanism; determining at which point to locate a joint or bearing in a mechanism; recognizing useful mechanisms in the students' communities that employ the same guided motion they have been studying.

In this Cyberchase video segment, the CyberSquad must locate each other using a map's grid to construct a coordinate system using letters and numbers.

Addition of three Vectors, and displays resultant Vectors. Can drag the endPoints of the three different Vectors, but the resultant always starts at the origin.

My pre-Calculus students were having trouble visualizing what it meant for a geometric series to converge. They understood the formula aspect and how to calculate the value of a convergent sum, and saw what it meant for numbers adding successively, but I

Ms. Whicker uses similar figures, 3D views and cross-sectional views to have her students construct figures using manipulatives.

This short video and interactive assessment activity is designed to teach second graders about visually evaluating parallel lines cut by a traversal.