This task suggests methods of introducing and continuing choral counting in the classroom.

Teachers (and then students) lead the class in chanting numbers from 1 to 120.

The purpose of this task is for students to find different pairs of numbers that sum to 7.

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.

Although this task is fairly straightforward, it is worth noticing that it does not explicitly tell students to look for intersection points when they graph the circle and the line. Thus, in addition to assessing whether they can solve the system of equations, it is assessing a simple but important piece of conceptual understanding, namely the correspondence between intersection points of the two graphs and solutions of the system.

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.

This short video and interactive assessment activity is designed to give fourth graders an overview of angles.

This short video and interactive assessment activity is designed to teach fourth graders about classifying all types of triangles by lengths of sides.

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 fourth graders about classifying triangles based on equal sides.

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

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

This activity is a classroom and schoolyard investigation where students collect daily temperature and precipitation readings, weather observations, and weekly phenology reports in a phenology binder and in nature journals. Students then analyze this data and compare to recorded values in the Weatherguide calendar.

In this task using a number line, students must partition the interval between 0 and 1 into eighths.

Students in math and business classes work together in groups to evaluate and compare cost and environmental performance of different clothes washers.

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In these math problems, students will examine the characteristics of water droplets in clouds.