I have recently blogged about Ada Lovelace and her paper doll which could be used as a history piece in a history of mathematics center that students can learn about mathematics and how math was developed back in the day. Today, are some activities that you can use in your classroom that revolve around paper dolls and mathematics.
Patterns: Figures alternate, for example: right arm up, left arm up, right arm, left arm.
Reflections: Students love that every doll is a flipped copy of the one next to it. Technically, that's called a reflection, one of three kinds of geometry transformation students study in elementary school, the other two being rotation and translation.
Powers of Two: Fold the paper twice, you get four figures. Fold the paper three times, you get 8 figures. Fold four times, you get 16 figures. Every fold is a power of two of the figures.
Multiplying fractions: Every time you fold, the dolls become half as wide. That's a visual illustration of what it means to multiply a fraction, in this case x 1/2. Or, if the first fold divides the paper in half, and the second fold divides it in quarters.
Learn more here: Paper Doll Math
View other activities and information here:
Math Manipulatives
Geometry of Folding
Probability
Showing posts with label multiply. Show all posts
Showing posts with label multiply. Show all posts
Calculating Weather Probability
There is a 30% chance of rain on Saturday, how did they come up with that percentage.
Forecasts issued by the National Weather Service routinely include a "PoP" (probability of precipitation) statement, which is often expressed as the "chance of rain" or "chance of precipitation".
An example of this:
ZONE FORECASTS FOR NORTH AND CENTRAL GEORGIA NATIONAL WEATHER SERVICE PEACHTREE CITY GA 119 PM EDT THU MAY 8 2008
GAZ021-022-032034-044046-055-057-090815-CHEROKEE-CLAYTON-COBB-DEKALB-FORSYTH-GWINNETT-HENRY-NORTH FULTON-ROCKDALE-SOUTH FULTON-INCLUDING THE CITIES OF...ATLANTA...CONYERS...DECATUR...
EAST POINT...LAWRENCEVILLE...MARIETTA 119 PM EDT THU MAY x 2008
.THIS AFTERNOON...MOSTLY CLOUDY WITH A 40 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS. WINDY. HIGHS IN THE LOWER 80S. NEAR STEADY TEMPERATURE IN THE LOWER 80S. SOUTH WINDS 15 TO 25 MPH. .TONIGHT...MOSTLY CLOUDY WITH A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE EVENING...THEN A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS AFTER MIDNIGHT. LOWS IN THE MID 60S. SOUTHWEST WINDS 5 TO 15 MPH. CHANCE OF RAIN 40 PERCENT.
What does this "40 percent" mean? ...will it rain 40 percent of of the time? ...will it rain over 40 percent of the area?
The "Probability of Precipitation" (PoP) describes the chance of precipitation occurring at any point you select in the area.
How do forecasters arrive at this value?
Mathematically, PoP is defined as follows:
So... in the case of the forecast above, if the forecaster knows precipitation is sure to occur ( confidence is 100% ), he/she is expressing how much of the area will receive measurable rain. ( PoP = "C" x "A" or "1" times ".4" which equals .4 or 40%.)
But, most of the time, the forecaster is expressing a combination of degree of confidence and areal coverage. If the forecaster is only 50% sure that precipitation will occur, and expects that, if it does occur, it will produce measurable rain over about 80 percent of the area, the PoP (chance of rain) is 40%. ( PoP = .5 x .8 which equals .4 or 40%. )
In either event, the correct way to interpret the forecast is: there is a 40 percent chance that rain will occur at any given point in the area.
Explaining "Probability of Precipitation": http://www.srh.noaa.gov/ffc/?n=pop
You can have your students multiple percentages and come up with their own weather forecast for the surrounding area for the next couple of days and see if the weatherman in your area are more accurate at predicting than you are.
Do you think you could put more real-world scenarios in your classroom? Is this a good example to start with in your room?
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