How do the area and perimeters of circles and squares compare? A clever video illustrates the change in the area of a circle and square while their total perimeter stays the same. The task is for learners to predict the point where the...

Not all structures take the shape of a polygon. The 21st lesson in a series of 29 shows young mathematicians they can create polygons out of composite shapes. Once they deconstruct the structures, they find the area of the composite figure.

Students investigate the area of squares and circles. In this geometry instructional activity, students calculate the area and probability of simple events. They work on a laptop using Safari.

What is an annulus? Pupils first learn about how to create an annulus, then consider how to find the area of such shapes. They then complete a problem set on arc length and areas of sectors.

This activity is a follow-on activity to inscribing a square in a circle. The overall problem is more complex. It deals with geometric constructions, properties of triangles, and regular hexagons. The final part of the activity...

Young scholars explore circles. For this algebra/geometry lesson, students discover the formula for the area of a circle, as they investigate the ratio of the area of a circle to the radius^2.

Going around in circles trying to find a resource on sectors of circles? Here is an activity where pupils first complete an assessment task to determine the areas and perimeters of sectors of circles. They then participate in an...

Through the use of Internet, video, and hands-on activities, youngsters learn the parts and characteristics of a circle. This fantastic lesson plan has some excellent website activities included in the plan. Your kids will have a much...

High schoolers analyze relationship between the increase in polygons sides and a circle. In this geometry lesson, students relate the size of the central angle of a polygon, to a circle. They compare the formula for the area of a polygon...

You've just hit the jackpot of integrating math problems and riddles with this jumbo-sized resource! Written as a newsletter, scroll through 35 pages of puzzles and quality problems to engage and encourage your learners to inquire...

Explore lines tangent to a circle. In this math lesson, students manipulate circles and lines on a TI calculator. They draw a circle  and analyze perpendicular lines intersecting the circle in only one place. This activity works...

Explore Apple's spaceship office building. Built in the shape of a circle, the office building offers a unique floor plan challenge. Young scholars use the dimensions of the building to estimate the square footage for each employee. 

Using Cabri Jr. high schoolers construct a circle and determine the equation of the circle they drew by finding the center and the radius. Students use the distance formula to derive the equation of their circle.

Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...

High schoolers construct the circumcenter of a triangle. In this constructing the circumcenter of a triangle lesson, students construct a triangle using Cabri Jr. High schoolers draw perpendicular bisectors of the sides of the triangle....

Young mathematicians explore the concept of triangles as they construct altitudes of triangles to find the orthocenter. Learners construct their triangles using Cabri Jr. on their graphing calculators and find that the altitudes of a...

After completing a task involving examining the ratio of areas of triangles and circles in a given figure, scholars examine sample responses to identify other strategies they could use to solve the problem.

For this geometry lesson on cylinders, geometers explore how to find the smallest surface area for a given volume.  They use their knowledge to relate it to the real world by making a model of a livestock tank.

Students explore different size circles to discover the relationship between diameter and circumference. In this circles and Pi lesson, students construct simple parachutes using circle patterns of varying sizes. Students predict the...

Solids come in many shapes and sizes. Using geometry, scholars create two-dimensional cross-sections of various three-dimensional objects. They develop the lesson further by finding the volume of solids. The module then shifts...

Sew up pupil interest with an engaging, hands-on lesson. Learners first design a sports bag given constraints on the dimensions of fabric. They then evaluate provided sample responses to identify strengths and weaknesses of included...

Math whizzes use the area probability applet to manipulate the size of the circle and the rectangle to explore the probability that a point in the rectangle is also in the circle.

High schoolers investigate properties of the four centers of a triangle and explore a special property of the circumcenter and orthocenter of a triangle. This lesson requires the use of Cabri, Jr.

Student find the area of a sector of a circle. In this geometry lesson, high schoolers  define the sector of a circle using a sketch. They find and identify examples of sector in the real world.