EXPERIMENT OBJECTIVES AND CONTENT

In this activity, students explore the differentaspects of body hair and head hair.

ESSENTIAL KNOWLEDGE

• External anatomy of human beings

SUGGESTED MATERIALS

Scientific equipment:• Magnifying glasses• Binocular magnifiers• Microscopes

Perishable non-scientific materials:• Gloves and masks (in case of allergies)

Household materials:• Mirrors• Tweezers• Animal hairs (cat, dog, etc.)• Head hair

School supplies:• Sheets of white paper• Large sheets of paper• Glue• Color felt pens• Rulers

CONTEXT: SITUATIONAL PROBLEM OR RESEARCH QUESTION

Have you ever noticed that many animals are covered with hair or fur? Is animal fur like thehair on your head? And what about the hair on your body. Is it different from animal hair? Is your hair the same as your friends’ hair?

ACTIVITY 3

IS BODY HAIR THE

SAME AS THE HAIR

ON YOUR HEAD?

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MAKE SURE YOU HAVE GLOVES AND MASKS

ON HAND FOR STUDENTS WHO ARE ALLERGIC

TO ANIMAL HAIR.

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SUGGESTED PREPARATORY ACTIVITIES (INTRODUCTION)

The teacher might suggest that the students findor learn funny expressions related to hair or fur(see references: hair quotes).

INITIAL IDEAS AND HYPOTHESES

Here are a few examples of hypotheses the studentsmight formulate based on their initial ideas:

Example 1I predict that I can tell what color a person’s bodyhair is by looking at the color of the hair on theirhead. I predict this because my body hair and thehair on my head are the same color.

Example 2I predict that if I take hairs from different parts ofmy body, they will all have the same characteristics.I predict this because only head hair is differentfrom body hair.

Example 3I predict that if a student has curly hair, his or herbody hair will be curly too. I predict this because headhair and body hair are the same, but since body hairsare shorter, we don’t notice that they are curly too.

Example 4I predict that if I compare my body hair with hairfrom my cat or dog, I will see differences. I predictthis because my pet’s hair is long and black, while I have red hair and the hair on my body is short.

WORK PLAN AND EXPERIMENTATION

Here are a few examples of experiments the studentscan carry out to verify their hypotheses:

Example AThe students observe hairs from their head and arm with the naked eye, a mirror, a magnifying glass,a binocular magnifier or a microscope. They describethe hairs and compare them with their friends’ hairs,and note the differences and similarities (color, length,thickness, texture, strength).

RECORD ALL YOUR IDEAS AND OBSERVATIONS

IN YOUR EXPERIMENT WORKBOOK.

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Example BThe students take samples of hair from their arm,leg and eyelashes, observe them and draw them ona piece of paper. They compare them to determine if they are alike.

Note: If the students want to observe an eyebrowhair or an eyelash, it is recommended that an adulttake the sample using tweezers. Some people caneasily remove an eyelash or eyebrow hair directlywith their fingers.

Example CThe students observe and compare head and bodyhair from a student with very curly hair with thoseof a student with straight hair.

Example DThe students observe and compare their body andhead hair with hair from various animals.

EXPERIMENTAL FACTORSTo ensure scientific rigor, the students should evaluate the experimental factors that might influence the experimental results.

• Subjectivity of perception

DISCUSSION: SUGGESTED INTEGRATION ACTIVITIES (CONSOLIDATION)

The students will be better able to answer the initialquestion if they combine their results. Were the students able to verify their hypotheses? They mustuse their results to justify their answers. Were theyable to explain why some head hair is straight andsome is curly? The students could affix the varioushead and body hairs used in their experiments tolarge sheets of paper, noting for each sample thename of the student and the observed characteristics.

SUGGESTED ACTIVITIES FOR APPLYING KNOWLEDGE (APPLICATION)

It might be fun to have a hairdresser come to the class, or to visit a hair salon near the schoolto gather information on, for example, hair caremethods (hair color, perms, etc.).

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SCIENTIFIC CONCEPTUAL CONTENT

“I adore your new body haircut.” Many languagesuse different words for body hair and head hair.For instance, French speakers use the word “poil”for body hair, while “cheveux” refers to head hair.Other languages, including English (“hair”) andGerman (“haar”), use a single word for both.

Structure of hairHair has two main components: an unseen portioncalled the root about 4 mm beneath the surface of the skin, and a visible portion called the shaft,which varies in length and emerges from an orificecalled a “pore.” Beneath the skin, a hair ends in abulb-like structure called the follicle, which has ahollow area at its base called the papilla. This connectswith blood vessels that carry the nutrients requiredfor hair growth.

Role of hairHair has a number of functions that are still poorly understood. It is used as a protective barrier in the nose and ears, for example. Armpit and genital hair may contribute to the evaporation ofperspiration and release of pheromones. In animals,hair plays an essential role in protecting againstcold or heat. The lead, mercury and arsenic contentof hair would seem to indicate that it also plays arole in detoxification.

Brown, black, blond or redHair roots and shafts are made up of three concentriccylinders: the medulla in the centre, which is surrounded by the melanin- and keratin-rich cortex,which is in turn surrounded by the cuticle, whichalso contains a great deal of keratin. Melanin is apigment responsible for color, while keratin is a protein that hardens the dead, flattened cells thatmake up the cortex and cuticle of hair.

Different ethnic origins, different hairHair with a nearly round cross-section is straight(common in Asians), while a more oval cross-sectionresults in more wavy hair (often seen in Europeans),and an elongated oval cross-section makes frizzy,or “kinky” hair (common in Africans).

Over 120,000This is the average number of hairs on your head (it can be as high as 150,000), for a total surfacearea of 6 square meters and a weight ranging from5 to 200 g. A single strand of hair is 50 to 100 µm in diameter, and hair grows at a rate of 0.3 mm per day–about 1 cm per month or 12 cm per year.If you placed all your hairs that grew in a year endto end, they would stretch 13 km.

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Hair growth and lossHair growth occurs when cells divide quickly in thefollicle to form a new hair. New hair grows onto the older hair, which is now made up of dead cells,until it eventually falls out. A hair will keep growingfor an average of three years. Every day, we losebetween 50 and 100 hairs. Unlike animals, humanhair does not grow synchronously, so there is alwayssome hair falling out while new hairs grow in. This iswhy we don’t generally notice that we lose hair.Heredity, the season, metabolism (lack of vitaminsand minerals), certain medical treatments, and hormones are all factors that affect hair growth.

Goose bumpsBetween the follicle and the epidermis (the surface ofthe skin) is a small muscle that can contract to makethe hair stand on end and give us goose bumps.

CULTURAL REFERENCES

HistoryHair has always been very important in human life.For ancient Egyptians, the type of wig you woreindicated your social status. In antiquity, hair couldbe a symbol of seduction in women (e.g., Aphroditewas “clothed” by her hair) and of strength in men(e.g., Samson, an Israelite hero with superhumanstrength). Hair was also used as an offering to thegods. Long hair was a symbol of virility and liberty forthe Gauls, while for certain Native American tribes,the scalp was considered a war trophy. Louis XIIIstarted the trend to wear long, curly wigs in France.After World War I, feminists initiated the first “bob cut”to assert their equality with men. In modern westernculture, hairstyles have become an expression ofpersonal conviction.

FOR MORE CULTURAL REFERENCES,

VISIT THE ÉCLAIRS DE SCIENCES WEBSITE:

www.eclairsdesciences.qc.ca

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ConceptionL’île du savoir (CRÉ de Montréal)

REFERENCES

Barrilé, Albert. Le corps humain. Paris: Hachette jeunesse, 2004.

École Petite Bourgogne. “Expressions et dictons sur le poil: Mots, expressions et proverbes se rapportant au corps humain.” In Commission scolaire de Montréal. [Website, undated]www.csdm.qc.ca/petite-bourgogne/vocabulaire/expressioncorpsp.htm#poil. Consulted August 15, 2007.

L’Oréal. “Les cheveux: un poil?” In L’Oréal Hair Science. [Website, 2005] www.hair-science.fr/_int/_fr/topic/topic_sousrub.aspx?tc=root-hair-science%5eamazingly-natural%sehair-fur&cur=hair-fur. Consulted August 15, 2007

Centre national de la recherche scientifique. “Jusqu’au bout des cheveux et des ongles.”In Dossiers Scientifiques ! Sagascience. Chimie Beauté. [Website, undated]www.cnrs.fr/cw/dossiers/doschim/decouv/cheveux/index.html. Consulted August 15, 2007.

Cité des sciences et de l’industrie. “Exposition: Le cheveu se décode.”In Cité des sciences et de l’industrie. [Website, 2002] www.cite-sciences.fr/francais/ala_cite/expo/tempo/cheveu/index.html. Consulted August 15, 2007.

UBR. “hair Quotes.” In Quotes Home. [Website, 2007].www.quotes.ubr.com/subject-quotes/h/hair-quotes.aspx. Consulted October 30, 2008.

All Quotes. “Hair Quotes.” In WorldofQuotes.com. [Website, 2006].www.worldofquotes.com/topic/Hair/index.html. Consulted October 30, 2008.

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process of active discovery general learning process in science and technology (in elementary school)

© 2011 /REV0202EN

My initial ideas:• I share my own ideas.

My hypothesis:• I predict that... I think that because…• I imagine my prototype.• I think it works like this…

My equipment:• I observe and handle the equipment.• How could this equipment be useful to me?• I choose my equipment and my materials.

Carrying out my process:• What will the steps be?• What precautions should I take?

My actions:• I carry out the steps of my protocol.• I note or draw what I observe, what I do and what I discover.

My results:• What is my answer to the problem, question or need?

• Situation problem or

• Discovery question or

• Need to be fulfilled

• Question related to the operation of an object (how does it work?)

My outcome:• Do my results confirm my hypothesis or not? • Are my results similar to those of the other teams?• Can the other teams' results help me to find answers to my problem, my question or my initial need?

• What could I communicate concerning my discoveries?

What I learned:• What do I retain from this activity?• What could I communicate concerning my results or my discoveries?

Context relatedto everyday life

Initial ideasand hypothesis

Planning and carrying out

Outcome

New question?