This short video and interactive assessment activity is designed to teach third graders about identifying the properties of squares.
If two inscribed angles intercept the same arc, then the angles are equal. Drag the orange points to change the figure.
An interactive applet and associated web page that demonstrate the inscribed angle of a circle - the angle subtended at the periphery by two points on the circle. The applet presents a circle with three points on it that can be dragged. The inscribed angle is shown and demonstrates that it is constant as the vertex is dragged. Links to other related topics such as Thales Theorem. 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 how to inscribe a circle in a triangle using angle bisectors. A companion task, ``Inscribing a circle in a triangle II'' stresses the auxiliary remarkable fact that comes out of this task, namely that the three angle bisectors of triangle ABC all meet in the point O.
This task is primarily for instructive purposes but can be used for assessment as well. Parts (a) and (b) are good applications of geometric constructions using a compass and could be used for assessment purposes but the process is a bit long since there are six triangles which need to be constructed.
This task provides an opportunity for students to apply triangle congruence theorems in an explicit, interesting context.
This problem introduces the circumcenter of a triangle and shows how it can be used to inscribe the triangle in a circle. It also shows that there cannot be more than one circumcenter.
This task focuses on a remarkable fact which comes out of the construction of the inscribed circle in a triangle: the angle bisectors of the three angles of triangle ABC all meet in a point.
This lesson unit is intended to help teachers assess how well students are able to use geometric properties to solve problems. In particular, it will help you identify and help students who have difficulty: decomposing complex shapes into simpler ones in order to solve a problem; bringing together several geometric concepts to solve a problem; and finding the relationship between radii of inscribed and circumscribed circles of right triangles.
An interactive applet and associated web page that demonstrate the relationship of the interior and exterior angles of a polygon. The applet shows an irregular polygon where one vertex is draggable. As it is dragged the interior and exterior angles at that vertex are displayed, and a formula is continuously updated showing that they are supplementary. The tricky part is when the vertex is dragged inside the polygon making it concave. The applet shows how the relationship still holds provided you get the signs of the angles right. 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 article is about the isoperimetric theorem. It states the theorem, explains its history and uses examples and exercises to demonstrate it. The resource is from PUMAS - Practical Uses of Math and Science - a collection of brief examples created by scientists and engineers showing how math and science topics taught in K-12 classes have real world applications.
This task is closely related to very important material about similarity and ratios in geometry.
Students will be able to use their knowledge of volume and surface area through this fun, hands-on activity.
This lesson unit is intended to help you assess how well students are able to: Perform arithmetic operations, including those involving whole-number exponents, recognizing and applying the conventional order of operations; Write and evaluate numerical expressions from diagrammatic representations and be able to identify equivalent expressions; apply the distributive and commutative properties appropriately; and use the method for finding areas of compound rectangles.
Students explore in detail how the Romans built aqueducts using arches—and the geometry involved in doing so. Building on what they learned in the associated lesson about how innovative Roman arches enabled the creation of magnificent structures such as aqueducts, students use trigonometry to complete worksheet problem calculations to determine semicircular arch construction details using trapezoidal-shaped and cube-shaped blocks. Then student groups use hot glue and half-inch wooden cube blocks to build model aqueducts, doing all the calculations to design and build the arches necessary to support a water-carrying channel over a three-foot span. They calculate the slope of the small-sized aqueduct based on what was typical for Roman aqueducts at the time, aiming to construct the ideal slope over a specified distance in order to achieve a water flow that is not spilling over or stagnant. They test their model aqueducts with water and then reflect on their performance.
In addition to the purely geometric and trigonometric aspects of the task, this problem asks students to model phenomena on the surface of the earth.
An interactive applet and associated web page that demonstrate the definition of a line. The applet presents two points and a line that passes through them extending to infinity in both directions. As the points a re dragged the line moves but it is never possible to reveal a line end. See also the entries for line segment and ray. 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 a bisector of a line segment. The applet shows a fixed line segment and another line that bisects it. The second line's endpoints can be dragged, but the line adjusts itself so that it always bisects the fixed line. 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 activity, students explore the relationship among angles formed by a transversal and a system of two lines. In particular, they consider what happens when the two lines are parallel versus when they are not.
This short video and interactive assessment activity is designed to teach fifth graders about determining whether various shapes have lines of symmetry.