Everyone Grows Up on Their Own Timetable

Adolescence is the whole stage of life between childhood and adulthood, covering roughly the ages of 10 to 19 years. Puberty is the period within it when the body matures and becomes capable of reproduction. So adolescence is the longer stage, and puberty is the set of changes that happen during it.

This page covers everything in the CBSE Class 7 Science chapter on adolescence: what the stage means, the physical changes of puberty, the hormones that cause them, and the facts about menstruation.

Because the timing and pace of these changes differ from person to person, and that variation is entirely normal.

Some students begin puberty at 9 or 10, others not until 14 or later. Two classmates of exactly the same age can be at completely different stages, and neither is early or late in any way that matters. The changes also happen at different speeds — one person's growth spurt may last a year, another's longer.

On average, girls tend to begin these changes a little earlier than boys, which is why girls of the same age are often taller for a few years before boys catch up.

For example, in any Class 7 classroom you can see a wide range of heights among students born within months of each other — a direct result of this variation.

The point to hold on to: there is no "correct" age. Comparing yourself with a friend tells you nothing useful about your own health or growth.

Several changes happen together, all driven by the body maturing.

There is a rapid increase in height and weight, often called the growth spurt. Hands and feet may grow before the rest of the body, which is why movements can feel clumsy for a while.

The voice changes. In boys the voice box enlarges, producing a visible bulge in the throat and a deeper voice, sometimes cracking as it settles. In girls the voice box grows less, and the voice becomes somewhat lower.

Hair grows in new areas, including under the arms and on other parts of the body, and in boys on the face.

The skin glands become more active, producing more oil and sweat. Blocked oil glands cause pimples and acne, which is very common at this stage and is not caused by any particular food or by poor character.

For example, a voice cracking mid-sentence during a classroom reading is simply the voice box growing, and it settles on its own.

These changes are temporary stages of a process, not permanent problems — which is worth remembering when any one of them feels uncomfortable.

Secondary sexual characteristics are the features that develop at puberty and distinguish mature males and females, apart from the reproductive organs themselves.

In girls, the breasts develop and the hips widen. In boys, the shoulders broaden, the chest widens, facial hair appears and the voice deepens.

These changes are brought about by hormones — chemical messengers released by endocrine glands directly into the blood. The blood carries them around the body, so a gland in one place can control a change somewhere else entirely.

The pituitary gland in the brain releases hormones that signal the reproductive organs to become active, and those organs then release the hormones responsible for the secondary characteristics. Testosterone in boys and oestrogen in girls are the main ones.

So the sequence runs: gland → hormone → blood → change in the body. That is why these changes cannot be hurried or delayed by effort; they follow the body's own signals.

Hormones also control other things entirely, such as growth and how the body uses food, which is why the endocrine system is studied as a whole later on.

The menstrual cycle is a normal, healthy monthly process in girls and women. A cycle lasts about 28 days, though anywhere from about 21 to 35 days is common, and bleeding lasts about 3 to 7 days.

Each month the lining of the uterus thickens in preparation for a possible pregnancy. When that does not occur, the lining is shed along with some blood and leaves the body — that is menstruation. The cycle then begins again.

The first period is called menarche and marks the start of this stage. Cycles are often irregular for the first year or two before settling into a pattern, which is normal.

Several myths need correcting plainly, because they cause real harm:
- Menstruation is not an illness or impurity. It is a sign of a healthy, working body.
- Girls can bathe, wash their hair, exercise, play sports and attend school as usual during their period.
- There is no food that must be avoided, and no reason to be kept away from the kitchen or from anyone.
- Mild discomfort or cramps are common; severe pain is worth discussing with a doctor or a trusted adult rather than simply enduring.

So the whole process is ordinary biology, and there is nothing shameful in it — which is exactly why it is taught in science class alongside every other body process.