Demonstrates how to add two 2-digit numbers, with no regrouping, using drawings of base ten cubes to represent 1s and 10s. [3:16]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Demonstrates how to add 37 + 2 using drawings of base ten cubes to represent 1s and 10s. [2:36]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

In this video segment from Cyberchase, Harry must adjust his dinner budget after his cousin, Harry, unexpectedly decides to join him on his date

Students develop a physical understanding for the meaning of equality by trying to find equal lengths using rods.

This task helps students broaden and deepen their understanding of the equals sign and equality.

Students can practice their addition, subtraction, multiplication, and division facts playing hidden picture. Learners solve the math problems to investigate the picture behind the flashcards.

Find a quick, concise explanation of how to add and subtract with negatives. Step by step examples are included to help you understand how to find the sum or difference when negative numbers are involved.

This lesson introduces subtraction operations in vectors. It is 5 of 5 in the series titled "Vector Subtraction." [3:46]

Take a look at this instructional video to learn about one of the most fundamental properties of math, the associative property. [5:13]

The commutative property only works for addition and multiplication. Watch this tutorial to learn the definition and see examples of how to use it. [4:11]

This tutorial defines the commutative property and provides examples of how to use it for addition and multiplication. [4:11]

Explore the relationship between addition and subtraction with this lesson. Help students understand that "every subtraction fact has a related addition number sentence, and every addition fact has a related subtraction number sentence".Lesson includes pictures and documents to help you implement the lesson.

This WebMath site shows how to add, subtract, multiply and divide through a step by step examples. The user simple selects the operation and types in two numbers, and the computer solves the problem through a step by step process. Also demonstrates fractions, ratios, and more.

This video features Harry and his cousin Harley. Harley is desperate to use Harry's bike, but first he must decipher the combination to the bike lock by solving a word problem. In the accompanying classroom activity, students complete a code-cracking activity of their own.

Watch Sal solve one addition word problem and one subtraction word problem in this video. [3:37]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

In the construction industry, being able to make calculations like adding and subtracting is an important part of many jobs.