Positive and Negative Numbers

  Last night, I thought about how we use positive and negative numbers in real life, yet we teach it using a horizontal number line.

We teach  children to count in a positive or negative  direction based on the numerical sign.  Even now when students stumble, I place a dot on the board and point in a direction, to prompt them.

I don't think we spend much time giving students context for applying these two concepts to real life.

We have mountains we can see from the porch of our school.  Its nice to connect positive numbers to climbing it since we are increasing elevation, and negative numbers to going down because elevation is decreasing.  The same could be applied to airplanes as the rise to their cruising altitude or descending to land on the ground. 

The stock market gives regular reports with positive and negative numbers as the Dow Jones shoots up or drops.  Daily temperatures rise or drop depending on the time of day. There are times when both the high and the low are negative numbers so the rising would be the positive part and dropping would be the negative.

Population growth can use positive numbers indicating it is growing or negative because the population looked at is declining.  Most people discuss weight as gaining or loosing it both number which fall into today's topic.  In addition credit card balances are shown with positive (items purchased) or negative (amount paid). 

The situation that hits most of us immediately is our bank account with deposits causing our accounts to increase, or withdrawals causing our accounts to decrease.  If we spend enough, we could owe the bank because we know have a negative balance.

Even general elevations such as Mount Whitney in California is over 14,000 feet above sea level while Death Valley is over 200 feet below sea level.  Then we have high and low tides, especially the Bay of Fundy which has tremendous differences.

Everyday, we hear words that indicate the use of positive and negative numbers such as "I'm short this month" meaning a negative amount compared to the amount needed.  I traveled 80 miles further than I anticipated today which is + 80 miles.

I think I'm going to use this topic as a welcome back to school activity where I have students brainstorm all the uses we have for positive and negative numbers.  There are so many situations my students could relate to.  Yeah.

Let me know what you think.