This task examines the ways in which the plane can be covered by regular polygons in a very strict arrangement called a regular tessellation. These tessellations are studied here using algebra, which enters the picture via the formula for the measure of the interior angles of a regular polygon (which should therefore be introduced or reviewed before beginning the task). The goal of the task is to use algebra in order to understand which tessellations of the plane with regular polygons are possible.

Students play and record the “Mary Had a Little Lamb” song using musical instruments and analyze the intensity of the sound using free audio editing and recording software. Then they use hollow Styrofoam half-spheres as acoustic mirrors (devices that reflect and focus sound), determine the radius of curvature of the mirror and calculate its focal length. Students place a microphone at the acoustic mirror focal point, re-record their songs, and compare the sound intensity on plot spectrums generated from their recordings both with and without the acoustic mirrors. A worksheet and KWL chart are provided.

In this game activity students practice comparing shapes and naming something that is alike or different about them.

Are your students having difficulty understanding math terminology? Try this A-Z glossary on math related terms. It's quick, easy to read, and very complete.

This task provides a construction of the angle bisector of an angle by reducing it to the bisection of an angle to finding the midpoint of a line segment. It is worth observing the symmetry -- for both finding midpoints and bisecting angles, the goal is to cut an object into two equal parts. The conclusion of this task is that they are, in a sense, of exactly equivalent difficulty -- bisecting a segment allows us to bisect and angle (part a) and, conversely, bisecting an angle allows us to bisect a segment (part b). In addition to seeing how these two constructions are related, the task also provides an opportunity for students to use two different triangle congruence criteria: SSS and SAS.

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

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

Find out how angles and symmetry come into play in the game of pool in this video adapted from Annenberg Learner’s Learning Math: Measurement.

The famous story of Archimedes running through the streets of Syracuse (in Sicily during the third century bc) shouting ''Eureka!!!'' (I have found it) reportedly occurred after he solved this problem. The problem combines the ideas of ratio and proportion within the context of density of matter.

In this problem, students are given a picture of two triangles that appear to be similar, but whose similarity cannot be proven without further information. Asking students to provide a sequence of similarity transformations that maps one triangle to the other focuses them on the work of standard G-SRT.2, using the definition of similarity in terms of similarity transformations.

This short video and interactive assessment activity is designed to give fourth graders an overview of composite figures composed of squares and rectangles.

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

In this video tutorial lesson, determine the area of a parallelogram using triangles and rectangles then assess learning with a quiz. [3:34]

In this video, students will determine the area of a trapezoid and assess learning with a quiz. [4:24]

In this video, students will use triangles to determine the area of a trapezoid. Assess learning with a quiz. [7:20]

This video tutorial shares several examples of different types of triangles as they are used to determine the area of each triangle. Assessment checks understanding. [6:54]

This problem is part of a very rich tradition of problems looking to maximize the area enclosed by a shape with fixed perimeter. Only three shapes are considered here because the problem is difficult for more irregular shapes.

The purpose of this task is primarily assessment-oriented, asking students to demonstrate knowledge of how to determine the congruency of triangles.

In this lesson, students will explore self-portraiture by looking at classical portrait paintings, such as Diego Velazquez's La Infanta Margarita or Raphael's Portrait of Baldassare Castiglione. A close look at these works reveals mathematical relationships and proper proportions that students can incorporate into their own self-portraits.