Adolescence: A Stage of Growth and Development

Why This Matters

Have you noticed something in the last year or two?

Maybe you have grown taller. Maybe your clothes feel a little short now. Maybe a friend’s voice has changed. Maybe a few pimples appeared on your face. Maybe you feel happy one minute and low the next, for no clear reason.

If any of this sounds like you, take a deep breath. Nothing is wrong. In fact, everything is going exactly the way nature planned it.

You are growing up. Your body is slowly changing from a child’s body into an adult’s body. This special time of change has a name. It is called adolescence.

Every adult you know has been through it — your parents, your teachers, even your favourite cricketer. It is one of the most normal things in the whole world. But because nobody talks about it much, it can feel confusing or even scary.

This chapter is here to clear up that confusion. We will explain, gently and honestly, what is happening to your body and why. By the end, you will understand these changes — and feel calm and confident about them.

The Big Idea

Adolescence is the stage of life when a child’s body slowly grows and changes into an adult’s body. It usually happens between about 10 and 19 years of age. During this time the body grows fast, it starts to look different, and the emotions get stronger. These changes are driven by tiny chemicals called hormones, made inside the body. Every healthy person goes through adolescence, but each person does it at their own pace and in their own time. Different timing is completely normal. There is nothing to be ashamed of and nothing to fear — this is simply the body getting ready to be an adult.

Let’s Break It Down

What is adolescence and puberty?

Think about how a plant grows. A seed sprouts into a tiny seedling. The seedling grows taller, gets more leaves, and one day it makes flowers, fruits and new seeds. It cannot make seeds the moment it sprouts. It first has to grow up.

Humans are the same. A newborn baby cannot have children. The body first has to grow and become mature. Mature means fully grown and ready. This growing-up takes years.

A human life can be split into stages. Figure 6.1 below lays them out as a simple timeline.

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Look at the highlighted stage in the middle. That is adolescence. It sits between childhood and adulthood. A person in this stage is called an adolescent (or a teenager). It usually runs from about age 10 to age 19.

Until about age 10 or 12, most changes are simply about getting taller and heavier. After that, new changes begin. The body starts preparing to become an adult. This preparation is called puberty.

Puberty is the stage during which the body of a child changes — on the outside and on the inside — into the body of an adult who can one day have children. Adolescence is the whole stretch of years; puberty is the set of body changes that happen during it.

Physical changes during adolescence

Let us look at the changes you can actually see and feel. None of these is strange. They happen to almost everybody. Figure 6.2 below gathers the common ones together.

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Let us go through them one by one.

Increase in height. Your body has been getting taller since birth. But during adolescence, the height increase becomes much faster. This is why your clothes seem to get short so quickly. Different people get their growth spurt at different times, so it is normal to be taller or shorter than a friend of the same age.

Changes in body shape, weight and strength. As boys grow, their shoulders may get broader and their chest may get wider. They also gain weight and strength. Girls also grow taller and gain weight, and their bodies develop in their own way, such as the development of breasts. These are natural changes as the body becomes an adult body.

Change in voice. Inside your throat is the voice box — the part that helps you make sound when you speak. During adolescence it grows. In boys it grows more, so the voice often becomes deeper and may sound hoarse or crack for a while. The growth can show up as a bump in the throat called the Adam’s apple, though not everyone has a clear one. The voice box grows a little in girls too, so their voice changes slightly.

Growth of body hair. Both boys and girls grow new hair in places like the armpits and the pubic region (the area between the legs). Boys often grow facial hair too, which slowly becomes a moustache and beard. How much hair grows, and when, is different for each person. All of this variation is completely normal.

Pimples on the skin. During adolescence the skin makes more oil than before. Sometimes this oil blocks the tiny holes in the skin (called pores) and causes small reddish bumps. These are pimples, and the skin condition is called acne. They appear most often on the face. They are very common and nothing to worry about. Washing your face gently and keeping it clean helps.

Here is the single most important thing to remember about all these changes:

The exact timing, nature, and amount of these changes is different for every single person. Whether it is height, voice, hair or anything else — early or late, more or less — all of it is completely normal. Each person experiences adolescence at his or her own pace.

Some of these visible changes — like a deeper voice or facial hair in boys, and breast development in girls — are not directly part of having children. But they help tell males and females apart as adults. For this reason they are called secondary sexual characteristics. They are natural signs that the body is preparing for adulthood, and they mark the start of puberty.

There are also changes you cannot see, happening deep inside the body, as the parts involved in having children slowly become mature. One important inside change in girls is the start of the menstrual cycle.

The menstrual cycle is a natural process in a girl’s body. Roughly every 28 to 30 days (it can be anywhere from 21 to 35 days and still be perfectly healthy), the body goes through a cycle. During one part of the cycle, a small amount of blood passes out of the body. This part is called menstruation, often just called “the period”. It usually lasts about three to seven days. Some girls feel a little pain or discomfort in the lower stomach during these days. Menstruation is a healthy, natural sign that the body is working well. It usually begins at puberty and stops naturally later in life, around age 45 to 55.

Menstruation is a normal, natural process — a sign of good health, not something to fear or feel ashamed about. Sadly, there are many wrong beliefs (myths) about it that cause needless fear, shame or guilt. One harmful old practice is keeping a girl apart from others during her period. There is no science behind such beliefs at all. We will look at clearing up myths a little later in this chapter.

The hormones and glands behind the changes

Now the big question. Why do all these changes suddenly start at this age, and not earlier? Why does the body know to begin?

The answer is hormones.

A hormone is a chemical messenger made inside your body. Think of it like a text message. A hormone is made in one place, then it travels through your blood to another part of the body, and it tells that part what to do. For example, a hormone can tell your bones, “Time to grow taller now.”

These messengers are made by special body parts called glands. A gland is a small organ whose job is to make and release a useful chemical. Figure 6.3 below shows where some of these glands sit and how they work.

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Here is the chain of events, step by step:

1. The brain acts like a control room. At the right time, it sends a signal.
2. This signal reaches the glands.
3. The glands make hormones and release them into the blood.
4. The blood carries the hormones around the body.
5. The hormones reach different parts and tell them to change — grow taller, deepen the voice, and so on.

So you do not have to decide to grow up. Your body does it automatically, controlled by hormones, at the right time. Some hormones even affect your mood and your feelings — which is why your emotions can feel stronger during these years (more on that next).

One gland worth knowing is the thyroid gland, found in the neck. It needs a mineral called iodine from food to work properly. This is why we use iodised salt. If you remember the boy and girl in the chapter’s exercises who each got a bump on the neck — one of those was caused by the thyroid gland not getting enough iodine.

Emotional and social changes

Adolescence is not only about the body. Your feelings and your behaviour change too — and this is just as normal.

During these years, emotions often become stronger than they were in childhood. You may feel very happy and full of energy on one day, and low or upset on the next, sometimes without a clear reason. These ups and downs are called mood swings. They are partly caused by the same hormones that change your body.

You may also feel more sensitive, or care more deeply about things. You might suddenly love music, art, sport, or a new hobby. You might want to do something good for others, like helping people in need. These are wonderful parts of growing up.

The trick is to understand your feelings instead of being controlled by them. When you notice “I am feeling low today” or “I am very excited,” you can pause and make a thoughtful choice about what to do next. Doing things you enjoy — sport, music, dance, reading, helping others — is a healthy way to handle strong emotions.

Your social life changes too. You may feel closer to your friends and want to spend more time with them. You may want to copy what your friends do. A lot of this happens online today. That is fine, but it means you must be thoughtful and responsible — both in person and on social media.

Two important social rules for this age:

• Be respectful and kind, online and offline. Think before you post. Never share personal photos or private information with strangers.
• If anyone tries to bully you (online bullying is called cyberbullying) or pressures you to do something wrong, do not feel scared or helpless. Tell a trusted adult — a parent or a teacher. Asking for help is a strong and smart thing to do, not a weak one.

Staying healthy — diet, hygiene, exercise and sleep

Your body is growing fast, so it needs good care. The good news is that staying healthy is mostly about a few simple daily habits. Figure 6.4 below shows them together.

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1. Eat a balanced diet. Because your body is building itself, food matters more than ever. A balanced diet means eating the right mix of all nutrients, not just one kind. Figure 6.5 below shows what a healthy plate looks like.

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Here is what each food group does. The table below makes it clear.

Food source	Nutrient you get	What it does for you
Milk, curd, paneer, cheese, millets	Calcium, proteins, fats	Helps bones grow strong
Dal, eggs, fish, soya, paneer	Proteins	Builds the body, gives strength and energy
Spinach, kidney beans, raisins, figs	Iron	Helps the body make blood
Roti, rice, millets, potato	Carbohydrates	Gives day-to-day energy to play and study
Fruits and many vegetables	Vitamins and minerals	Keep the body working well and fight illness

One special note: adolescents, especially girls, sometimes get weak or tired because of a shortage of iron in the body (this can cause a blood problem called anaemia). Eating iron-rich foods like spinach, beans and raisins helps. The government even runs schemes to give children iron and other nutrients.

2. Keep clean (personal hygiene). Hygiene means keeping your body and surroundings clean to stay free of illness. During adolescence the body sweats more and the skin makes more oil, so daily cleaning matters. Bathe daily, and clean carefully in areas like the armpits and the pubic region, which can otherwise get infections. Wash your face gently to help with pimples.

For girls, keeping clean during menstruation is important for both comfort and health. This is done using items made for the purpose, such as sanitary pads or clean reusable cloth pads, and changing them regularly. Used pads should be wrapped (for example in newspaper) and put in a dustbin, to keep everyone healthy and the surroundings clean. The government provides sanitary pads free or cheaply through several schemes so that every girl can stay healthy. Menstrual hygiene is a normal health need, and there is nothing shameful about it.

3. Exercise and physical activity. Playing games, sports and exercising regularly keeps your body fit and strong. It builds stamina (the ability to keep going without getting tired), and it also lifts your mood. So when you play cricket or run around with friends, you are doing your body and mind a big favour.

4. Get enough sleep. A growing body needs good rest. Sleeping well (about eight hours) helps your body grow, helps your brain learn, and keeps your mood steady. Late nights on a phone leave you tired and cranky the next day.

5. Say NO to harmful substances. Some people — even friends — may pressure you to try harmful things like tobacco, gutka, cigarettes, beedi, alcohol or drugs. These are addictive. Addictive means that once you start, the body develops a strong urge to keep taking it again and again, and stopping becomes very hard. They damage your body and mind. The safest choice is to never try them, not even once. Say NO firmly and confidently — and if you ever feel trapped, talk to a parent or teacher. There is even a national helpline, 14446, to help with addiction.

Myths versus facts

Because people did not always understand adolescence, many wrong beliefs grew up around it. A myth is a belief that many people hold but that is not actually true. Myths can cause fear, shame and unfair treatment for no good reason. Let us replace some common myths with the facts. Figure 6.6 below puts them side by side.

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The table below lays these out again so you can read the reasoning slowly.

The myth (not true)	The fact (true)
Everyone changes at exactly the same age.	Each person changes at their own pace. Being early or late is normal and healthy.
A girl is impure during menstruation and must be kept apart.	Menstruation is a normal, healthy process. There is no scientific basis for such taboos.
Pimples can be cured by scrubbing the face very hard.	Hard scrubbing makes acne worse. Gentle, regular cleaning and patience help.
Trying a harmful substance once is harmless; you can quit anytime.	These substances are addictive. Many addicted people started with just one try.
Mood swings mean something is wrong with you.	Mood swings are caused by active hormones and are a normal part of growing up.

The big lesson here is to think scientifically. When you hear a belief about the body, ask: is there any real reason behind this, or is it just an old myth? A scientific outlook clears away needless fear and shame.

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Summary

• Adolescence is the stage of life between childhood and adulthood, usually from about 10 to 19 years of age. A person in this stage is an adolescent.
• During adolescence the body grows fast and changes into an adult body. Puberty is the name for these body changes.
• Physical changes include an increase in height, changes in body shape and strength, a change in voice (the voice box grows), more body hair, and pimples on the skin. Their timing and amount differ for everyone, and all of it is normal.
• Features that tell males and females apart but are not directly used in having children are called secondary sexual characteristics.
• In girls, adolescence brings the menstrual cycle, which includes menstruation — a normal, healthy process with no reason for fear or shame.
• Adolescence also brings emotional and social changes — stronger feelings, mood swings, and closer friendships — which are all normal.
• The changes are controlled by hormones, chemical messengers made by glands and carried by the blood, started by a signal from the brain.
• Staying healthy means eating a balanced diet, keeping good personal hygiene, getting exercise and enough sleep, saying NO to addictive substances, and clearing away myths with a scientific outlook.

What’s Next

You have just seen how your own body changes and grows. Next, we turn from the body to the world around it — and to one of the most important things in all of nature: heat.

In Chapter 7 — Heat Transfer in Nature, you will find out what heat really is, how it moves from a hot thing to a cold thing, and why a metal spoon in hot tea soon feels hot at the other end too. You will see how heat travels through solids, through liquids and air, and even across empty space from the Sun. It explains everyday things you already notice — why we wear light clothes in summer, why the sea breeze blows, and much more.