The purpose of this task is to help students understand what is meant by a base and its corresponding height in a triangle and to be able to correctly identify all three base-height pairs.

This short video and interactive assessment activity is designed to teach third graders an overview of lines, curves, vertices, and sides of 2d shapes.

This short video and interactive assessment activity is designed to teach second graders an overview of lines, curves, vertices, and sides of 2d shapes.

This short video and interactive assessment activity is designed to give fifth graders an overview of simple figure patterns.

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

This short video and interactive assessment activity is designed to teach third graders an overview of simple figure patterns.

This short video and interactive assessment activity is designed to teach second graders an overview of simple figure patterns.

This task provides the most famous construction to bisect a given angle. It applies when the angle is not 180 degrees.

In this lesson students will explore shape sorting by attributes using a variety of media.

Students find the volume and surface area of a rectangular box (e.g., a cereal box), and then figure out how to convert that box into a new, cubical box having the same volume as the original. As they construct the new, cube-shaped box from the original box material, students discover that the cubical box has less surface area than the original, and thus, a cube is a more efficient way to package things. Students then consider why consumer goods generally aren't packaged in cube-shaped boxes, even though they would require less material to produce and ultimately, less waste to discard. To display their findings, each student designs and constructs a mobile that contains a duplicate of his or her original box, the new cube-shaped box of the same volume, the scraps that are left over from the original box, and pertinent calculations of the volumes and surface areas involved. The activities involved provide valuable experience in problem solving with spatial-visual relationships.

To display the results from the previous activity, each student designs and constructs a mobile that contains a duplicate of his or her original box, the new cube-shaped box of the same volume, the scraps that are left over from the original box, and pertinent calculations of the volumes and surface areas involved. They problem solve and apply their understanding of see-saws and lever systems to create balanced mobiles.

This task applies reflections to a regular hexagon to construct a pattern of six hexagons enclosing a seventh: the focus of the task is on using the properties of reflections to deduce this seven hexagon pattern.

This task applies reflections to a regular octagon to construct a pattern of four octagons enclosing a quadrilateral: the focus of the task is on using the properties of reflections to deduce that the quadrilateral is actually a square.

Student pairs are given 10 minutes to create the biggest box possible using one piece of construction paper. Teams use only scissors and tape to each construct a box and determine how much puffed rice it can hold. Then, to meet the challenge, they improve their designs to create bigger boxes. They plot the class data, comparing measured to calculated volumes for each box, seeing the mathematical relationship. They discuss how the concepts of volume and design iteration are important for engineers. Making 3-D shapes also supports the development of spatial visualization skills. This activity and its associated lesson and activity all employ volume and geometry to cultivate seeing patterns and understanding scale models, practices used in engineering design to analyze the effectiveness of proposed design solutions.

This book is a "flexed" version of CK-12's Basic Geometry that aligns with College Access Geometry and contains embedded literacy supports. It covers the essentials of geometry for the high school student.

Includes chapters on: Basics of Geometry, Reasoning and Proof, Parallel and Perpendicular Lines, Triangles and Congruence, Relationships with Triangles, Polygons and Quadrilaterals, Similarity, Right Triangle Trigonometry, Circles, Perimeter and Area, Surface Area and Volume, Rigid Transformations.

This Geometry Concept Collection is a rigorous presentation of high school geometry. It is fully correlated with the Common Core State Standards.

CK-12 Middle School Math Concepts for seventh grade provides a complete textbook. It presents topics including algebraic thinking, patterns, decimals, decimal operations, fractions, fraction operations, integers, integer operations, ratios, rates, proportions, percents, percent applications, equations, solving equations, inequalities, functions, graphing functions, geometry, plane geometry, solid geometry, area, perimeter, surface area, volume, statistics including mean, median, mode and range, graphing and types of graphs, and probability.

CK-12 Foundation's Geometry FlexBook is a clear presentation of the essentials of geometry for the high school student. Topics include: Proof, Congruent Triangles, Quadrilaterals, Similarity, Perimeter & Area, Volume, and Transformations.

The purpose of this task is to use geometric and algebraic reasoning to model a real-life scenario. In particular, students are in several places (implicitly or explicitly) to reason as to when making approximations is reasonable and when to round, when to use equalities vs. inequalities, and the choice of units to work with (e.g., mm vs. cm).