Thursday, October 10, 2013

Learning Negative Numbers

Learning about negative numbers is a topic that can baffle kids at first glance, but negative numbers have real life application. Here are some examples to help negative numbers make a little more sense.

  • Floors in a Building
In Europe, the ground floor of a building is floor zero. Going up the floors are typically numbered consecutively; 1, 2, 3, 4 and so on. Going down they would be referred to as 1 under, 2 under, 3 under, 4 under and so on. The floors underground could also be referred to in the negative.

If the building superintendent was working on the furnace on floor 4 underground and was called to a toilet emergency on floor number 3, how many floors would he need to go up?  -4 + number of floors to climb = 3 => 7 floors

  • Debt
If money is owed to somebody, that could be viewed as money not had, or negative money.

Justin bought a television on credit and agreed to a price of $500. He had -$500. His paycheck totaled $1200. How much money did Justin get to keep? Answer: $1200-$500=$700.

  • Sea Level
It is common to refer to elevation in feet above sea level. In the Rocky Mountains some mountains reach elevations of 12,000 ft. Since the elevation is measured from sea level, that makes sea level 0 ft. Therefore, depths of the ocean are measured in feet below sea level which could also be referred to in terms of negative numbers.

The hull of the ship was found at a depth of 50 ft. The treasure was found at 75 ft. The winch used to haul in treasure stood on the top deck of the ship, 40 feet above sea level. How long of a rope was needed to recover the treasure? Answer: -75 ft + length of rope = 40 ft => length of rope = 115 ft

  • Temperature
In America we typically measure air temperature in degrees Fahrenheit. On cold winter days in northern states temperatures can fall below zero also referred to in negative numbers.

John's new iPod worked at 32 degrees Fahrenheit. The temperature outside was 5 below zero. The temperature was expected to rise 45 degrees throughout the day. Would his iPod work? Answer: -5+45=40 degrees => 40 degrees > 32 degrees, therefore his iPod would work.

  • Time
It is the year 2013 on our calendar. 2013 years ago was the year designated as year 0. In studying history, events that occurred before the year zero are often referred to as BC or before Christ. This time period can also be referred to in terms of negative numbers.

Alexander the Great was born in the year 356 BC. How many years ago was that? Answer: 2013-(-356)=2369 years ago.

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