KS3 · Biology

Puberty and sexual maturity

Some puberty changes happen to everyone and some to one sex only. Have a go at sorting them, then ask what they are all for.

SORT IT FIRST

Who gets which change?

Tick who each change happens to: males, females, or both. Watch the overlap fill up as you go, then check.

  • A Males
  • B Females
  1. Emotional changes
  2. A faster growth rate
  3. Stronger body odour
  4. Underarm hair starts to grow
  5. Pubic hair starts to grow
  6. The voice breaks and gets deeper
  7. Hair grows on the chest, and later on the face
  8. The shoulders widen as muscle mass increases
  9. The breasts develop
  10. The hips widen

THE REPRODUCTIVE SYSTEMS

Male reproductive systemvsFemale reproductive system

Puberty also changes the reproductive systems themselves. Compare how the two systems change side by side.

Focus

An organ starts its job

Male reproductive system

The testes start to produce sperm cells.

Female reproductive system

The ovaries start to release egg cells.

The insight

Each system starts something it was not doing before. That is what it means for a reproductive system to mature.

Another change

Male reproductive system

The testes and the penis get bigger.

Female reproductive system

The menstrual cycle begins: a roughly monthly cycle of events that prepares the female reproductive system for pregnancy. A period is part of it.

How they work

Male reproductive system

Works together with the female system to produce offspring.

Female reproductive system

Works together with the male system to produce offspring.

WHY PUBERTY?

?

Reason it through

Why does the body go through all these changes?

Link 1 of 4

First link · your turn

Something has to be in charge of changes in so many different places. What do you think it is?

2
Locked — reveal the link above first
3
Locked — reveal the link above first
4
Locked — reveal the link above first

TIMING

How quickly does puberty happen?

Two friends are chatting about puberty. One of them says something about how long it takes and when it starts.

Which is closest to what you think right now?
How sure are you?

YOUR TURN

Say it in your own words

Describe two changes of puberty that happen in both males and females, one that happens only in males and one that happens only in females. Then explain why these changes are necessary. [6 marks]

0 words · your answer stays on this page and is not sent anywhere.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Which changes happen to everyone, which to one sex only, and what they are all getting the body ready for.

What you need to know

  • Reproduction means producing offspring, and it is how a species continues into the next generation.
  • Humans have male and female reproductive systems that work together, but a child’s are not mature, so children cannot reproduce.
  • Puberty is the physical and emotional changes as a child becomes an adult, meaning a human who is able to reproduce.
  • Have a goYour cousin says, ‘Adult? That’s when you get a job and have to pay bills.’ In biology, what actually makes a human an adult here?

    Being able to reproduce.

    In this context an adult is a human who is able to reproduce. It is about what the body can do, not about jobs or bills.

  • Puberty takes place over several years, not overnight, and varies from person to person. Females generally start slightly earlier.
  • Have a goTwo friends begin puberty a year apart. Has one of them got it wrong?

    No. When puberty starts and ends varies between individuals.

    Puberty is a stage lasting several years, and timing varies from person to person, so a different start is normal variation.

  • Sex hormones are chemical messengers, released by the ovaries in females and the testes in males, and they control the changes.
  • Have a goA pupil says, ‘Only females have sex hormones, because only females have ovaries.’ What is wrong with that?

    Males have them too: the testes release the sex hormones in males.

    Sex hormones are released by the ovaries in females and by the testes in males, so both sexes have them.

  • These changes mature the reproductive systems, and other changes also prepare the body for reproduction and adulthood.
  • In males, the testes and penis get bigger and the testes start to produce sperm cells.
  • In females, the ovaries start to release egg cells and the menstrual cycle begins.
  • Both sexes: emotional changes, faster growth, stronger body odour, and underarm and pubic hair.
  • Only males: voice breaks and deepens, chest then facial hair, wider shoulders. Only females: breasts develop, hips widen.

The big picture

Puberty is the set of physical and emotional changes that take place as a child becomes an adult, which in biology means a human who is able to reproduce. Some changes happen in both sexes, some only in males and some only in females. Sex hormones control them, and together they mature the reproductive systems and prepare the body for reproduction. It is a stage lasting several years, not an overnight switch.

Key points

1Puberty is the physical and emotional changes as a child becomes an adult, meaning a human who is able to reproduce.
2Some changes happen in both sexes, some only in males and some only in females, and together they prepare the body for reproduction.
3Sex hormones, released by the ovaries and the testes, control the changes, and the reproductive systems mature as a result.
4In males the testes start to produce sperm cells. In females the ovaries start to release egg cells and the menstrual cycle begins.
5Puberty takes place over several years, varies from person to person, and females generally start slightly earlier.

Worked example

Problem

A pupil is asked, ‘Why does the body go through puberty?’ and writes: ‘Because you grow faster and your voice changes.’ Turn that into a proper biological answer.

⚠ Watch out

Thinking puberty is one event that arrives for everyone on the same day, or that males and females share nothing. It is a stage lasting several years, its timing varies from person to person, females generally start slightly earlier, and many changes happen in both sexes.

🧠

Memory hook

Sort every change into Both, Males only or Females only, then ask what the whole lot is for. Every pile leads to the same place: a body that is able to reproduce.

✓

Check yourself

A friend says the testes and ovaries ‘do the same thing’ in puberty. What does each one actually start to do, and what do they have in common?

Flashcards

(14)
What is reproduction?
The process of producing offspring. It allows a species to continue by making the next generation.
What are reproductive systems?
Organs whose function is reproduction. The male and female systems work together to produce offspring.
Why can a child not produce offspring?
Their reproductive systems are not mature.
What is puberty?
The physical and psychological (emotional) changes that take place when a child becomes an adult.
In puberty, what does ‘adult’ mean?
A human who is able to reproduce.
How long does puberty last, and when does it happen?
A stage of the life cycle that takes place over several years. When it starts and ends varies from person to person, and females generally start slightly earlier.
What is a hormone?
A chemical messenger, released by a gland and transported around the body.
Where do the sex hormones come from?
The ovaries in females and the testes in males.
How does the male reproductive system change in puberty?
The testes and penis get bigger, and the testes start to produce sperm cells.
How does the female reproductive system change in puberty?
The ovaries start to release egg cells and the menstrual cycle begins.
What is the menstrual cycle?
A roughly monthly cycle of events that prepares the female reproductive system for pregnancy. A period is part of it.
Name the changes that happen in both males and females.
Emotional changes, an increase in growth rate, stronger body odour, and growth of underarm hair and pubic hair.
Name the changes that happen only in males.
The voice breaks and gets deeper, hair grows on the chest and later the face, and the shoulders widen as muscle mass increases.
Name the changes that happen only in females.
The breasts develop and the hips widen, which prepares the hips for childbirth.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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How this lesson was checked. This KS3 Biologylesson was published through Lightbulb Learning's human-designed editorial process — the educational standards, accuracy rules and publication checks it must pass were authored and approved by Philip Halpin. It passed subject-specific assessment, automated educational checks and technical publication verification before going live (publication checks completed 9 October 2026). Published pages are monitored, human spot-checking is ongoing across the lesson library, and anything found wrong is corrected or withdrawn. How our lessons are made and checked. Spotted a mistake? Email hello@lightbulblearning.co and we'll review it.