Before you start your investigation you should carry out a risk assessment and have it checked by your teacher. For help with this, read through our health and safety information and look out for health and safety warnings in the text.
There are lots of different liquids that we use to clean things. In this project you can do some experiments to see why we use shampoo to wash our hair. You will investigate how different shampoos affect the appearance of different hair types.
Start by thinking about shampoo and other liquid cleaning products. What shampoos do you and your friends use? Why do they choose them? Why don’t we wash our hair with washing-up liquid or liquid soap?
You might want to visit a hairdresser and ask why they use certain shampoos on certain hair types.
Looking in more detail
Most school microscopes use low magnification. In other words, they can’t see really small things. To see things under a high magnification you need to use an oil immersion lens. Ask your teacher how to do this. You could also try gaining access to a powerful microscope, perhaps by speaking to your local hospital. This will allow you to look at your hair samples
in much greater detail.
Picking your samples
If you look around you’ll notice lots of different hair types – different colours, different levels of waviness and different thickness for example. You need to decide how many different hair types you’ll need to test in order to gain a fair representation of the population. You’ll also need to decide how many hairs make up one sample.
Are there any hygiene issues you need to consider?
Look at each of your hair samples under a powerful microscope before washing them. Describe what you see. For example, does the hair have split ends or raised cuticles? Is it the same thickness along the full length?
Washing the samples
Remember to keep all non-variables constant. For example, amount of cleaning product, temperature of water and method of drying.
You should test about three different shampoos on each hair type. You should also test other liquid cleaning products, such as washing-up liquid.
When the hair has been washed and dried, look at it again under the microscope:
- Has it changed? How?
- Did the different types of cleaner/shampoo make a difference?
- Did the type of hair make much difference?
- What are the pH values of the cleaning products you used? What difference do you think the pH value makes?
Extra variables – if you have time!
People don’t just wash their hair – they style it and colour it, too. So you could investigate the effect these sorts of treatments have on hair. Again, you’ll need to think about sampling a range of hair types. It’s up to you which sorts of treatment you want to look at. Some suggestions are, curling straight hair, blow-dying hair, or use of hairspray. You may want to test these over a period of time. In other words, see if prolonged use makes a difference. Again, remember to keep non-variables constant.
For a similar project at Bronze level try ‘Why do we use shampoo?’
For a similar project at Gold level try ‘What ’
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