Positive and Negative Numbers
Understand positive and negative numbers as describing quantities with opposite directions or values; use them in context such as temperature, floors in a building, and bank balances
What a learner can do afterwards
- Represent positive and negative numbers on a number line and explain what zero means in context
- Add a positive or negative number to any integer using number line reasoning
- Subtract a positive or negative number from any integer, understanding that subtracting a negative is equivalent to adding
The lesson
You already know how to read a thermometer, so you have a head start here. Numbers can go two directions from zero. Positive numbers sit above zero, like +5. Negative numbers sit below zero, like -3. Zero itself is the starting point that everything else is measured from.
A parking garage floor is labeled -2. The lobby is floor 0. The offices are on floor 3. Traveling from the parking garage to the offices means going up 5 floors: -2, -1, 0, 1, 2, 3.
Subtracting a negative number acts like adding. If you take away a $10 debt, you end up $10 richer. That is why 5 - (-10) gives the same answer as 5 + 10.
Positive numbers sit above zero, negative numbers sit below zero, and subtracting a negative number is the same as adding a positive one.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.