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Introduction
I get a few students contacting me looking for ideas on science
projects about hair each year. This can be difficult because hair
itself is rather uninteresting and does not do much. It doesn't
respond to stimuli, it's hard keratinized material, and it's dead.
It's like trying to think of something useful to do with nail
clippings (which are made of the same material). As adults are
obsessed with their hair, so kids inherit the interest sooner
or later and some want to do science fair projects about it. Personally,
I would much prefer to do some project involving creepy crawlies.
I also have the added problem that I was not educated in the US
education system. I grew up in Britain where you did what you
were told in science classes and woe betide anyone who had their
own idea for an experiment. So I am not familiar with science
fair projects or what exactly they entail. However, below are
a few ideas for projects involving hair based on studies that
professional scientists have done at some time in hair biology
history and some they may still do today for cosmetics companies.
Examining
hair cosmetics
Many kids want to do a project on hair cosmetics. The problem
with examining the effects of cosmetics on hair is that the changes
are very subtle and difficult to quantify. Cosmetics companies look
at hair quality by subjecting hair fiber to the cosmetic of interest
and then examining the results by electron microscopy or perhaps
chemical analysis. Both methods are expensive and not readily accessible
to most school teachers. Companies focus on what shampoo does to
the cuticle. Does the cuticle flake and crack easily? Does the cuticle
reflect light well and look shiny? These are subtle changes not
easily observed. Effects on hair by different shampoos or shampoo
versus "placebo" will not show quantifiable differences.
However, what students could do is mimic the semi quantifiable
data collection methods that cosmetic companies use. They can get
their friends to each try a different shampoo for a set length of
time, ask the users for their impressions and evaluate hair quality
from photos or visual examination using arbitrary scales for light
reflectance, manageability, feel during application, quality impression
by the user, and so on. This is not hard science but it can be made
into something that requires a lot of statistical analysis and it
requires good interpersonal skills.
Ideally such a project would involve many people using the same
shampoo to reduce the impact of the users' genetic hair quality.
Differences in hair care habits need to be standardized (How frequent
is washing? How long is the shampoo on the scalp? How old is the
hair that it is being applied to [sections of hair at the end of
long strands is several years old - the ends of short hair may be
a few months old]). Other things to consider will be what other
cosmetics do they use on their hair (conditioner)?, do they color/perm
hair?, how often do they comb the hair? How much exposure is there
to air pollution? and so on. Trying to standardize such a project
will not be easy but would certainly introduce students to the complexities
of experimental design and the kind of problems cosmetics testers
face.
Rather than looking at cosmetics that are similar (shampoos, conditioners)
you might consider looking at very different formulations such as
brilliantines and pomades versus hair gel and oil - water emulsions.
Or perhaps look at all-in-one shampoos and conditioners versus using
separate shampoo and conditioner from the same company. Which does
the focus group find superior and why?
Measuring
hair fiber strength under different conditions.
Hair takes on different properties depending on humidity and chemicals
it has been exposed to. You might try looking at the strength of
hair that has been treated in different ways. The basic system involves
tying a strand or maybe several strands of hair to a stand. At the
other end tie a hook that you can hang weights on. Put a ruler by
the side of the hair fiber and add the weight gradually. As you
gradually add the weight, you should see the hair fiber stretch
before it breaks. By measuring the length of hair at different weights
and plotting the results on a graph you should get a nice curve.
By recording the amount of weight it takes to break the hair you
can work out the hair strength.
To make things more interesting, take a few hair strands from someone
who does not chemically treat their hair and some strands from someone
who perms, bleaches, or permanently colors their hair. Ideally get
and use the treated hair within 24 hours of treatment (try the local
hair salon for volunteers). Compare the "stretchability"
of treated and untreated hair and the overall strength. Treated
hair should be weaker although if there is enough time between treatment
and testing the hair will recover its strength.
Additionally, look at the properties of wet and dry hair. Hair
immersed in water for an hour will swell by up to 20%. Ideally,
heat the water to 50 degrees centigrade get maximum absorption into
the hair. Test the strength of this wet hair versus "dry"
hair (not strictly dry as all hair takes in water to some degree
depending on air humidity). The wet hair should weaker by up to
30%. Hair strength in normal air humidity is somewhere between 1,000,000gm/cm
square to 1,250,000gm/cm square - as strong as copper wire of similar
diameter.
Hair
growth rates
Get an adult who normally shaves every day to let his (her?) beard
grow over the weekend or longer if possible. Ask them to shave off
the beard growth after a couple of days and collect the stubble.
If they wet shave, they can collect the stubble by shaving using
a bowel of water and then pouring the soap, water, and stubble into
a coffee filter paper. Pour a few cups of water through the paper
to wash away the soap and let the hair dry out. Then you need to
mount the hairs on several slides. You can do this properly by spreading
the hairs on slides using tweezers and applying some mounting medium
and a cover slip, or you can do it more quickly by using see through
sticky tape to tape over the slide and hold the hair fibers in place.
Here comes the exciting bit! The kids get to measure the individual
cut hairs and plot them on a chart! Use a microscope with an eyepiece
graticule to measure the lengths of individual fibers. You do not
have to measure all the individual hairs - you can use random sampling.
Random sampling means you measure say 100 hairs at random from the
slides.
You can estimate the rate of hair growth by adding up all the hair
lengths you measure and dividing by the number of hairs measured.
This should give you the average length of the hairs. If you know
how long the beard has been growing (2 days, 3 days etc.) then you
can work out the average rate of growth for beard hair. More advanced
students can work out the standard deviation and standard error
for the data. Beard growth rate varies from person to person and
depends on their health and age. The rate can be anything up to
0.4mm a day.
There are a couple of different ways you can plot the measurements
out on a chart. You could group the measurements into sets. For
example, you can make up size classes, 0-49 micrometers, 50-99 micrometers,
100-149 micrometers and so on. Count the number of fibers in that
are 0-49 micrometers in length and so on. You can the plot these
sets on a bar chart to show the range of hair sizes. You can also
do dispersion diagrams, plotting the different lengths of hair along
a line on graph paper. You could add marks to show the upper quartile,
median and lower quartile ranges. You can probably think of other
ways to plot the data too.
These kind of hair growth measurement studies were first done in
the 1920s and involved regular hair shaving by volunteers on all
parts of the body. Through time the studies have been repeated and
expanded such that we have a good idea of hair growth rates for
different parts of the body and differences due to age or sex. There
is a brief summary
table here.
Hair
loss measurement
Why not get kids to record the degrees of male (or even female)
pattern baldness? Use the standard Hamilton / Norwood scale found
on
this page. Feel free to download the pictures and print them.
Give the kids a copy of the picture each and have them observe passers
by, maybe from an elevated position. Have them look at perhaps 100
men and to record the person's extent of hair loss and their estimated
age. The children should be able to plot the extent of hair loss
against age and see a line. The kids should also be able to see
that the percentage of men with baldness increases with age. About
20% of men in their 20s have pattern baldness, 30% of men in their
30s and so on until about 60 years of age where the trend is lost.
If men have not lost their hair by 60 they are very unlikely to
do so.
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