This short video and interactive assessment activity is designed to teach third graders about word problems that compare values.

This short video and interactive assessment activity is designed to teach second graders about comparing with two-step addition and subtraction.

The purpose of this task is to foster a classroom discussion that will highlight the difference between multiplicative and additive reasoning.

The purpose of this task is to assess studentsŐ understanding of multiplicative and additive reasoning.

The purpose of this task is to help develop students' understanding of addition of fractions; it is intended as an instructional task.

In this video from Cyberchase, Harry must score a total of 50 points in various events to qualify for the Northern Hemisphere games in New Orleans.

In this Cyberchase video segment, Matt uses subtraction to help Digit figure out how much time he has left in a cooking contest with Hacker.

In these lessons students will explore the paintings of Horace Pippin and Wayne Thiebaud and the mobiles of Alexander Calder to discover and practice math and visual art concepts. Background and biographical information about the work of art and artist, guided looking with class discussion, and activities with worksheets using mathematical formulas and studio art provide the framework for each lesson.

Do you have a big decimals test coming up? Or are you studying for your standardized math test? This site is both fun and helpful! On this site you can review the following topics: place values of decimals, how to read decimals, expanded notation for decimals, and how to convert fractions into decimals. On this site you can also review how to add, subtract, multiply, and divide decimals. You will also learn about terminating and repeating decimals.

The Decimals Cruncher game will help you learn about decimal operations! You can choose to practice adding, subtracting, multiplying, or dividing. You can also pick how hard the game is. The game has 4 levels: easy, medium, hard, and killer. The Decimals Cruncher will keep track of your score. When you switch to a new operation (addition, subtraction, multiplication, or division), your score will start over again.

Sal discusses the conditions of matrix dimensions for which addition or multiplication are defined. Created by Sal Khan.

This short video and interactive assessment activity is designed to teach third graders an overview of subtraction (numbers to 1,000).

This short video and interactive assessment activity is designed to give fourth graders an overview of subtraction (numbers to 1,000).

This short video and interactive assessment activity is designed to teach second graders an overview of subtraction (numbers to 1,000).

This task helps students understand the meaning of the equal sign and to use it appropriately.

This short video and interactive assessment activity is designed to teach second graders about fact families (numbers to 1,000).

This short video and interactive assessment activity is designed to teach third graders about fact families (numbers to 1,000).

This task allows students to relate addition and subtraction problems to money in a context that introduces the concept of scarcity.