www.wyzant.com/resources/lessons/math/elementary_math/positive_and_negative_numbers/adding_positive_and_negative_numbers

Adding positive numbers to negative numbers can get tricky, because you need to pay close attention to where the negative signs are placed in the problem.

www.wyzant.com/resources/lessons/math/elementary_math/positive_and_negative_numbers/subtracting_positive_and_negative_numbers

Subtracting positive and negative numbers can also be tricky because there are several ... Thus, instead of subtracting a negative, you are adding a positive.

www.khanacademy.org/math/arithmetic/arith-review-negative-numbers/arith-review-sub-neg-intro/v/adding-and-subtracting-negative-number-examples

Learn how to add and subtract negative numbers. ... To have a positive or negative 0 (+0/-0) is really to have the same value, that is to say, nothing.

www.khanacademy.org/math/arithmetic/arith-review-negative-numbers/arith-review-add-negatives-intro/e/adding_negative_numbers

Practice adding positive and negative single-digit numbers.

www.mathsisfun.com/positive-negative-integers.html

Adding Positive Numbers. Adding ... Here is what adding and subtracting positive numbers looks like: ... You can add weights (you are adding negative values).

www.purplemath.com/modules/negative2.htm

When you'd subtracted a positive number, you'd moved to the left. Now, if you're adding a negative, you can regard this is pretty much the same as when you ...

nrich.maths.org/5947

How can we help students make sense of addition and subtraction of negative numbers?

learnzillion.com/lesson_plans/5250-adding-positive-and-negative-integers-on-a-number-line

In this lesson you will learn to add positive and negative integers by using a number line.