Khan Academy
Khan Academy: Add and Subtract Mixed Numbers (No Regrouping)
Practice adding and subtracting mixed numbers with common (like) denominators. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Calculator Soup
Calculator Soup: Adding and Subtracting Integers (Whole Numbers) Calculator
Use this calculator for adding and subtracting integers. Positive and negative whole numbers are integers. The calculator shows the work for the math and shows you when to change the sign for subtracting negative numbers.
CK-12 Foundation
Ck 12: Elem Math: Adding and Subtracting Terms Numbers to 100
[Free Registration/Login may be required to access all resource tools.] This is a tool that gives a video demonstration and follows up with a pratice activity that checks for understanding.
Khan Academy
Khan Academy: Adding & Subtracting Rational Numbers
Practice adding and subtracting negative fractions, decimals, and percents. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Adding & Subtracting Rational Numbers
Practice adding and subtracting rational numbers of different forms.
Khan Academy
Khan Academy: Add and Subtract Using a Number Line
Practice adding and subtracting numbers like 54 and 37 using a number line. Numbers used in these problems are all less than 100.
Khan Academy
Khan Academy: Add and Subtract Mixed Numbers (With Regrouping)
Practice adding and subtracting mixed numbers with common (like) denominators. Items require regrouping (borrowing).
Khan Academy
Khan Academy: Adding & Subtracting in Scientific Notation
Given two numbers in scientific notation, practice adding and subtracting them.
Khan Academy
Khan Academy: Add and Subtract on the Number Line Word Problems
Practice adding and subtracting using the number line. Numbers used are 100 or less.
Khan Academy
Khan Academy: Adding & Subtracting Rational Numbers
Practice adding and subtracting negative fractions, decimals, and percents.
Lawrence Hall of Science
The Math Page: Skill in Arithmetic: Add and Subtract Fractions
This Math Page tutorial explains how to add and subtract fractions and features a practice section at the very end of the lesson.
Khan Academy
Khan Academy: Adding & Subtracting Negative Fractions
Practice adding and subtracting positive and negative fractions.
Khan Academy
Khan Academy: Adding & Subtracting Negative Numbers
Practice solving addition and subtraction problems with integers (positive and negative numbers). Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
CK-12 Foundation
Ck 12: Elem Math: Adding and Subtracting Numbers Up to 20 Word Problems
[Free Registration/Login may be required to access all resource tools.] The video describes how to solve word problems using both addition and subtraction. The video is followed by additional practice problems.
Khan Academy
Khan Academy: Add and Subtract Within 100 Word Problems 1
Practice adding and subtracting to solve word problems. These questions are result unknown or change unknown problems. Numbers used are 100 or less. Students receive immediate feedback and have the opportunity to try questions...
Khan Academy
Khan Academy: Add and Subtract Within 100 Word Problems 1
Practice adding and subtracting to solve word problems. These questions are result unknown or change unknown problems. Numbers used are 100 or less.
Math Planet
Math Planet: Monomials and Adding or Subtracting Polynomials
Gain an understanding of how to add or subtract polynomials by viewing an example and a video lesson.
Other
Nearpod: Adding & Subtracting: Unlike Denominators
In this lesson, 5th graders will learn how to add and subtract fractions and mixed numbers using models and by finding common denominators.
Khan Academy
Khan Academy: Adding & Subtracting Negative Numbers
Practice solving addition and subtraction problems with integers (positive and negative numbers).
CK-12 Foundation
Ck 12: Elem Math: Adding and Subtracting Numbers Up to 20 Word Problems
[Free Registration/Login may be required to access all resource tools.] The video describes how to solve word problems where they have to add or subtract 3 or more numbers.
Khan Academy
Khan Academy: Add and Subtract Mixed Numbers (No Regrouping)
Practice adding and subtracting mixed numbers with common (like) denominators.
Houghton Mifflin Harcourt
Holt, Rinehart and Winston: Homework Help Independent Practice: Add and Subtract Rational Numbers 2
Get independent practice adding and subtracting fractions with unlike denominators. Each incorrect response gets a text box explanation and another try. Correct responses are confirmed.
Houghton Mifflin Harcourt
Holt, Rinehart and Winston: Homework Help Independent Practice: Add and Subtract Rational Numbers 1
Get independent practice adding and subtracting rational numbers. Each incorrect response gets a text box explanation and another try. Correct responses are confirmed.
Varsity Tutors 
Varsity Tutors: Hotmath: Algebra Review: Add and Subtract With Negatives
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.