Review of adding integers: counters, number line, different signs, rules - video lesson
This is a review lesson on integer addition for pre-algebra or 7th grade math.
First I briefly show the basics of integer addition using counters and number line.
Then we solve sums with more than two integers to add, starting with additions of several negative integers, and then proceeding to sums that include several negative and positive integers. The basic idea is to first add all the negatives and all the positives separately, and lastly add those two sums.
I also explain the common rules for integer addition. When the two integers have different signs, you subtract their absolute values, then check which "side wins" so to speak (which integer has larger absolute value), and the sum has the same sign as that integer.
Tengo una versión español de este video también.
See also
Subtraction of integers — a video lesson
Math Mammoth Integers — a self-teaching worktext with explanations & exercises for all operations with integers
Math Mammoth Grade 7 complete curriculum