Have you ever wondered how many hairs you have on your head or how to calculate how many hairs . Here is an easy method to do that,and lead you to some hair-raising conclusions.

Engaging Questions

• Does the color of your hair influence the number of hairs you have on your head?

• Does gender influence the number of hairs you have on your head?

• Does age influence the number of hairs you have on your head?

• Does the texture (coarse or fine) influence the number of hairs you have on your head?

• Does ethnicity influence the number of hairs you have on your head?

• Do the seasons influence the number of hairs you have on your head?

• Does climate influence the number of hairs you have on your head?

• Does your location influence the number of hairs you have on your head?

• Does genetics influence the number of hairs you have on your head?

• Do environmental factors influence the number of hairs on your head?

• Do physiological factors influence the number of hairs on your head?

Teacher Goals

• The students will observe people's heads and gather data through measurements.

• Using the hair equation, the student will calculate the total number of hairs on a person's scalp

Required Resources

• measuring tools metric tape measure metric ruler

Optional Resources

• calculator

• Counting tools
  
  Comb (Rat tail comb works well to part and lift hair)
  dull point pencil or blunt probe to lift hair from scalp

• Resources

  • Counting Hairs
  • Counting Hairs

Steps

1. Constant

   Select the same location on the person's scalp to use as the constant in the gathering of hair data on all test subjects.

2. Area Hair Step 1

   Lay the metric ruler along the constant location of the person's scalp and count the number of hairs along one centimeter. Record the number of hairs.

3. Area Hair Step 2

   Rotate ruler 90 degrees in same constant location on scalp and count the number of hairs along one cenimeter. Record the number of hairs.

4. Circumference

   Using the metric tape measure, find the distance in centimeters around the person's scalp.  This will be the circumference. Record the data (cm).

5. Total Scalp Surface Area

   Calculating Total Scalp Surface Area
   
   Area = circumference squared
   divided by 2 x 3.14
   
   Area =(Circumference)2
   2 
    

6. Calculating Total Number of Hairs

   Use the equation to calculate the total number of hairs on the scalp.

   Number of hairs/cm  x  Number of hairs/cm  x total surface area of scalp (cm squared)

   or
   Square centimeter area number of hairs  x total surface area of scalp

   Through the factor label method, the unit of centimeters squared is cancelled .
   Record the data

Teacher Notes

• Duration: Time is variable upon number of test subjects per student.
  One hair count and calculations will take approximately 30-35 minutes.