Math Games

There's this really great website that has free math games. It separates it by grades or type of math. For example they have first grade two digit addition. This website also has different math sheets teachers can print out and use for their class.

http://www.math-play.com/

Standard Deviation

Standard deviation shows the variation from your data. Here is a math problem to give an example of how to find standard deviation based on collected data.

Seven students on an intramural team weigh 148 lb, 155 lb, 143 lb, 154 lb, 145 lb, 164 lb and 141 lb. What is the standard deviation of the weight of these students.

1) Find the mean.
 148+155+143+154+145+164+141       = 150
                       7
2) Subtract the mean from each of the weights.
148-150 = -2
155-150 = 5
143-150 = -7
154-150 = 4
145-150 = -5
164-150 = 14
141-150 = -9

3) Square each of the differences from step 2.
(-2)^2 = 4
(5)^2 = 25
(-7)^2=49
(4)^2 = 16
(-5)^2 = 25
(14)^2 = 196
(-9)^2 = 81

4) Add up all your answers from step 3.
4+25+49+16+25+196+81 = 396

5)Divide the sum from step 4 by the number of weights to get the variance.
396   =56.571
 7

6) Square the answer from step 5 to find the standard deviation.
56.571 = 7.5
 7

Your standard deviation is 7.5

Mean, Median, and Mode

The figure below contains the salaries of different employees at a job. What is the mean, median, and mode.

Number           Type                       Salary
    1                 owner                    $26,900 
    5              Sales Person             $18,900
    3                Secretary                $16,100
    1               Custodian                $11,000


Mean
First you multiply the number of people in the area of work by the salary that area of work makes. This gives you the total cost for each area of work.

1 * 26,900 = 26,900
5 * 18,900 = 94,500
3 * 16,100 = 48,300
1 * 11,000 = 11,000

Then you add up all the total cost. This finds the sum of all the employees makings.

26,900 + 94,500 + 48,300 +11,000 = 180,700

Finally you divide it by the total number of employees. To Find your mean.

180,700  = 18,070
    10

Median
First you have to place all your salaries from least to greatest.

11,000    16,100    16,100    16,100    18,900    18,900    18,900    18,900    18,900    26,900

Then you find the one in the middle and that is your median.

Mode
The mode is the salary that appears the most.
In this case it is 18,900

Transforming Graphs

I learned how to turn a bar graph into a pie chart. I think its a good way to show your class how to use the same information in different ways. It also gives them different charts to chose from according to which one they feel more comfortable using.

How to turn a Bar Graph into a Pie Chart

1. You have to gather your data and make a bar graph out of it.
2. You cut the bars out and tape them all together in one long line.
3. You then connect the ends of the line together to create a circle.
4. You trace the circle and mark you data.
5. Finally you color it in and make a key.

 

 

Here is a great website to make free graphs and charts.
http://www.chartgo.com/